{"api_version":"1","generated_at":"2026-06-02T09:42:57+00:00","cve":"CVE-2026-45842","urls":{"html":"https://cve.report/CVE-2026-45842","api":"https://cve.report/api/cve/CVE-2026-45842.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-45842","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-45842"},"summary":{"title":"slip: reject VJ receive packets on instances with no rstate array","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nslip: reject VJ receive packets on instances with no rstate array\n\nslhc_init() accepts rslots == 0 as a valid configuration, with the\ndocumented meaning of 'no receive compression'. In that case the\nallocation loop in slhc_init() is skipped, so comp->rstate stays\nNULL and comp->rslot_limit stays 0 (from the kzalloc of struct\nslcompress).\n\nThe receive helpers do not defend against that configuration.\nslhc_uncompress() dereferences comp->rstate[x] when the VJ header\ncarries an explicit connection ID, and slhc_remember() later assigns\ncs = &comp->rstate[...] after only comparing the packet's slot number\nto comp->rslot_limit. Because rslot_limit is 0, slot 0 passes the\nrange check, and the code dereferences a NULL rstate.\n\nThe configuration is reachable in-tree through PPP. PPPIOCSMAXCID\nstores its argument in a signed int, and (val >> 16) uses arithmetic\nshift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1\nis 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because\n/dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path\nis reachable from an unprivileged user namespace. Once the malformed\nVJ state is installed, any inbound VJ-compressed or VJ-uncompressed\nframe that selects slot 0 crashes the kernel in softirq context:\n\n Oops: general protection fault, probably for non-canonical\n       address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519)\n Call Trace:\n  <TASK>\n  ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466)\n  ppp_input (drivers/net/ppp/ppp_generic.c:2359)\n  ppp_async_process (drivers/net/ppp/ppp_async.c:492)\n  tasklet_action_common (kernel/softirq.c:926)\n  handle_softirqs (kernel/softirq.c:623)\n  run_ksoftirqd (kernel/softirq.c:1055)\n  smpboot_thread_fn (kernel/smpboot.c:160)\n  kthread (kernel/kthread.c:436)\n  ret_from_fork (arch/x86/kernel/process.c:164)\n  </TASK>\n\nReject the receive side on such instances instead of touching rstate.\nslhc_uncompress() falls through to its existing 'bad' label, which\nbumps sls_i_error and enters the toss state. slhc_remember() mirrors\nthat with an explicit sls_i_error increment followed by slhc_toss();\nthe sls_i_runt counter is not used here because a missing rstate is\nan internal configuration state, not a runt packet.\n\nThe transmit path is unaffected: the only in-tree caller that picks\nrslots from userspace (ppp_generic.c) still supplies tslots >= 1, and\nslip.c always calls slhc_init(16, 16), so comp->tstate remains valid\nand slhc_compress() continues to work.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-05-27 11:16:23","updated_at":"2026-06-01 17:17:14"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/4aa9eca6fda2919027dfd7a7cc69334982d89586","name":"https://git.kernel.org/stable/c/4aa9eca6fda2919027dfd7a7cc69334982d89586","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/72304fec672e8aac9ee7b9c475db96b37cca8d8d","name":"https://git.kernel.org/stable/c/72304fec672e8aac9ee7b9c475db96b37cca8d8d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9e1ff0eead073c4f46d874ad2526b7dda5465faf","name":"https://git.kernel.org/stable/c/9e1ff0eead073c4f46d874ad2526b7dda5465faf","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/de42f86e2cf5028a97e74c25869d1a962b13c301","name":"https://git.kernel.org/stable/c/de42f86e2cf5028a97e74c25869d1a962b13c301","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e76607442d5b73e1ba6768f501ef815bb58c2c0e","name":"https://git.kernel.org/stable/c/e76607442d5b73e1ba6768f501ef815bb58c2c0e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c6980e8b1a86288167f34966fa5219031999b6f1","name":"https://git.kernel.org/stable/c/c6980e8b1a86288167f34966fa5219031999b6f1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152","name":"https://git.kernel.org/stable/c/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3d71c961febddd855d3ae9a519eeb96c8023f430","name":"https://git.kernel.org/stable/c/3d71c961febddd855d3ae9a519eeb96c8023f430","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-45842","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45842","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae 3d71c961febddd855d3ae9a519eeb96c8023f430 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae 72304fec672e8aac9ee7b9c475db96b37cca8d8d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae 4aa9eca6fda2919027dfd7a7cc69334982d89586 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae c6980e8b1a86288167f34966fa5219031999b6f1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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a1c3860d3c5fc62bd35f089bcb03f18a37242de9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f82699de104eaf8a7ffc2849a566a94818dd8a3c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 354b254af5c1350de9586af75fe5a821b35bfb33 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5148857f5d4c812cc918cf4627f7880521e987eb git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 82185755d90c8047c6f4b589c39998ff3d4ca3ad git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a50a93cc99286dc444c7e5ccc7dfb9d58c2d346d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6b4fa561e26526c62636414d267342c945084f44 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.32.70 2.6.33 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.2.75 3.3 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.4.111 3.5 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.10.96 3.11 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.12.53 3.13 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.14.60 3.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.18.27 3.19 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.1.17 4.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.3.5 4.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.4","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.258 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.209 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.175 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.141 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.91 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.33 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.10 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"45842","cve":"CVE-2026-45842","epss":"0.000180000","percentile":"0.050770000","score_date":"2026-06-01","updated_at":"2026-06-02 00:05:19"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/net/slip/slhc.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"3d71c961febddd855d3ae9a519eeb96c8023f430","status":"affected","version":"4ab42d78e37a294ac7bc56901d563c642e03c4ae","versionType":"git"},{"lessThan":"72304fec672e8aac9ee7b9c475db96b37cca8d8d","status":"affected","version":"4ab42d78e37a294ac7bc56901d563c642e03c4ae","versionType":"git"},{"lessThan":"4aa9eca6fda2919027dfd7a7cc69334982d89586","status":"affected","version":"4ab42d78e37a294ac7bc56901d563c642e03c4ae","versionType":"git"},{"lessThan":"c6980e8b1a86288167f34966fa5219031999b6f1","status":"affected","version":"4ab42d78e37a294ac7bc56901d563c642e03c4ae","versionType":"git"},{"lessThan":"de42f86e2cf5028a97e74c25869d1a962b13c301","status":"affected","version":"4ab42d78e37a294ac7bc56901d563c642e03c4ae","versionType":"git"},{"lessThan":"9e1ff0eead073c4f46d874ad2526b7dda5465faf","status":"affected","version":"4ab42d78e37a294ac7bc56901d563c642e03c4ae","versionType":"git"},{"lessThan":"7b0d9e878ec2b21d99ae8051b3dda59cdb66c152","status":"affected","version":"4ab42d78e37a294ac7bc56901d563c642e03c4ae","versionType":"git"},{"lessThan":"e76607442d5b73e1ba6768f501ef815bb58c2c0e","status":"affected","version":"4ab42d78e37a294ac7bc56901d563c642e03c4ae","versionType":"git"},{"status":"affected","version":"42fc512469e78939c1e419d3310c47de55bdcbb8","versionType":"git"},{"status":"affected","version":"df085f1cb3acd3d75408ff94f366983873bce7d2","versionType":"git"},{"status":"affected","version":"a1c3860d3c5fc62bd35f089bcb03f18a37242de9","versionType":"git"},{"status":"affected","version":"f82699de104eaf8a7ffc2849a566a94818dd8a3c","versionType":"git"},{"status":"affected","version":"354b254af5c1350de9586af75fe5a821b35bfb33","versionType":"git"},{"status":"affected","version":"5148857f5d4c812cc918cf4627f7880521e987eb","versionType":"git"},{"status":"affected","version":"82185755d90c8047c6f4b589c39998ff3d4ca3ad","versionType":"git"},{"status":"affected","version":"a50a93cc99286dc444c7e5ccc7dfb9d58c2d346d","versionType":"git"},{"status":"affected","version":"6b4fa561e26526c62636414d267342c945084f44","versionType":"git"},{"lessThan":"2.6.33","status":"affected","version":"2.6.32.70","versionType":"semver"},{"lessThan":"3.3","status":"affected","version":"3.2.75","versionType":"semver"},{"lessThan":"3.5","status":"affected","version":"3.4.111","versionType":"semver"},{"lessThan":"3.11","status":"affected","version":"3.10.96","versionType":"semver"},{"lessThan":"3.13","status":"affected","version":"3.12.53","versionType":"semver"},{"lessThan":"3.15","status":"affected","version":"3.14.60","versionType":"semver"},{"lessThan":"3.19","status":"affected","version":"3.18.27","versionType":"semver"},{"lessThan":"4.2","status":"affected","version":"4.1.17","versionType":"semver"},{"lessThan":"4.4","status":"affected","version":"4.3.5","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/net/slip/slhc.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.4"},{"lessThan":"4.4","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.258","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.209","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.175","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.141","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.91","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.33","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.10","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.1-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.258","versionStartIncluding":"4.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.209","versionStartIncluding":"4.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.175","versionStartIncluding":"4.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.141","versionStartIncluding":"4.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.91","versionStartIncluding":"4.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.33","versionStartIncluding":"4.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.10","versionStartIncluding":"4.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1-rc1","versionStartIncluding":"4.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32.70","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2.75","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.4.111","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10.96","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.12.53","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14.60","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18.27","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3.5","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nslip: reject VJ receive packets on instances with no rstate array\n\nslhc_init() accepts rslots == 0 as a valid configuration, with the\ndocumented meaning of 'no receive compression'. In that case the\nallocation loop in slhc_init() is skipped, so comp->rstate stays\nNULL and comp->rslot_limit stays 0 (from the kzalloc of struct\nslcompress).\n\nThe receive helpers do not defend against that configuration.\nslhc_uncompress() dereferences comp->rstate[x] when the VJ header\ncarries an explicit connection ID, and slhc_remember() later assigns\ncs = &comp->rstate[...] after only comparing the packet's slot number\nto comp->rslot_limit. Because rslot_limit is 0, slot 0 passes the\nrange check, and the code dereferences a NULL rstate.\n\nThe configuration is reachable in-tree through PPP. PPPIOCSMAXCID\nstores its argument in a signed int, and (val >> 16) uses arithmetic\nshift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1\nis 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because\n/dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path\nis reachable from an unprivileged user namespace. Once the malformed\nVJ state is installed, any inbound VJ-compressed or VJ-uncompressed\nframe that selects slot 0 crashes the kernel in softirq context:\n\n Oops: general protection fault, probably for non-canonical\n       address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519)\n Call Trace:\n  <TASK>\n  ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466)\n  ppp_input (drivers/net/ppp/ppp_generic.c:2359)\n  ppp_async_process (drivers/net/ppp/ppp_async.c:492)\n  tasklet_action_common (kernel/softirq.c:926)\n  handle_softirqs (kernel/softirq.c:623)\n  run_ksoftirqd (kernel/softirq.c:1055)\n  smpboot_thread_fn (kernel/smpboot.c:160)\n  kthread (kernel/kthread.c:436)\n  ret_from_fork (arch/x86/kernel/process.c:164)\n  </TASK>\n\nReject the receive side on such instances instead of touching rstate.\nslhc_uncompress() falls through to its existing 'bad' label, which\nbumps sls_i_error and enters the toss state. slhc_remember() mirrors\nthat with an explicit sls_i_error increment followed by slhc_toss();\nthe sls_i_runt counter is not used here because a missing rstate is\nan internal configuration state, not a runt packet.\n\nThe transmit path is unaffected: the only in-tree caller that picks\nrslots from userspace (ppp_generic.c) still supplies tslots >= 1, and\nslip.c always calls slhc_init(16, 16), so comp->tstate remains valid\nand slhc_compress() continues to work."}],"providerMetadata":{"dateUpdated":"2026-06-01T16:16:32.860Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/3d71c961febddd855d3ae9a519eeb96c8023f430"},{"url":"https://git.kernel.org/stable/c/72304fec672e8aac9ee7b9c475db96b37cca8d8d"},{"url":"https://git.kernel.org/stable/c/4aa9eca6fda2919027dfd7a7cc69334982d89586"},{"url":"https://git.kernel.org/stable/c/c6980e8b1a86288167f34966fa5219031999b6f1"},{"url":"https://git.kernel.org/stable/c/de42f86e2cf5028a97e74c25869d1a962b13c301"},{"url":"https://git.kernel.org/stable/c/9e1ff0eead073c4f46d874ad2526b7dda5465faf"},{"url":"https://git.kernel.org/stable/c/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152"},{"url":"https://git.kernel.org/stable/c/e76607442d5b73e1ba6768f501ef815bb58c2c0e"}],"title":"slip: reject VJ receive packets on instances with no rstate array","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-45842","datePublished":"2026-05-27T09:24:42.637Z","dateReserved":"2026-05-13T15:03:33.078Z","dateUpdated":"2026-06-01T16:16:32.860Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-05-27 11:16:23","lastModifiedDate":"2026-06-01 17:17:14","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"45842","Ordinal":"1","Title":"slip: reject VJ receive packets on instances with no rstate arra","CVE":"CVE-2026-45842","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"45842","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nslip: reject VJ receive packets on instances with no rstate array\n\nslhc_init() accepts rslots == 0 as a valid configuration, with the\ndocumented meaning of 'no receive compression'. In that case the\nallocation loop in slhc_init() is skipped, so comp->rstate stays\nNULL and comp->rslot_limit stays 0 (from the kzalloc of struct\nslcompress).\n\nThe receive helpers do not defend against that configuration.\nslhc_uncompress() dereferences comp->rstate[x] when the VJ header\ncarries an explicit connection ID, and slhc_remember() later assigns\ncs = &comp->rstate[...] after only comparing the packet's slot number\nto comp->rslot_limit. Because rslot_limit is 0, slot 0 passes the\nrange check, and the code dereferences a NULL rstate.\n\nThe configuration is reachable in-tree through PPP. PPPIOCSMAXCID\nstores its argument in a signed int, and (val >> 16) uses arithmetic\nshift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1\nis 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because\n/dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path\nis reachable from an unprivileged user namespace. Once the malformed\nVJ state is installed, any inbound VJ-compressed or VJ-uncompressed\nframe that selects slot 0 crashes the kernel in softirq context:\n\n Oops: general protection fault, probably for non-canonical\n       address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519)\n Call Trace:\n  <TASK>\n  ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466)\n  ppp_input (drivers/net/ppp/ppp_generic.c:2359)\n  ppp_async_process (drivers/net/ppp/ppp_async.c:492)\n  tasklet_action_common (kernel/softirq.c:926)\n  handle_softirqs (kernel/softirq.c:623)\n  run_ksoftirqd (kernel/softirq.c:1055)\n  smpboot_thread_fn (kernel/smpboot.c:160)\n  kthread (kernel/kthread.c:436)\n  ret_from_fork (arch/x86/kernel/process.c:164)\n  </TASK>\n\nReject the receive side on such instances instead of touching rstate.\nslhc_uncompress() falls through to its existing 'bad' label, which\nbumps sls_i_error and enters the toss state. slhc_remember() mirrors\nthat with an explicit sls_i_error increment followed by slhc_toss();\nthe sls_i_runt counter is not used here because a missing rstate is\nan internal configuration state, not a runt packet.\n\nThe transmit path is unaffected: the only in-tree caller that picks\nrslots from userspace (ppp_generic.c) still supplies tslots >= 1, and\nslip.c always calls slhc_init(16, 16), so comp->tstate remains valid\nand slhc_compress() continues to work.","Type":"Description","Title":"slip: reject VJ receive packets on instances with no rstate arra"}]}}}