{"api_version":"1","generated_at":"2026-04-19T01:14:02+00:00","cve":"CVE-2026-23397","urls":{"html":"https://cve.report/CVE-2026-23397","api":"https://cve.report/api/cve/CVE-2026-23397.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-23397","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-23397"},"summary":{"title":"nfnetlink_osf: validate individual option lengths in fingerprints","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfnetlink_osf: validate individual option lengths in fingerprints\n\nnfnl_osf_add_callback() validates opt_num bounds and string\nNUL-termination but does not check individual option length fields.\nA zero-length option causes nf_osf_match_one() to enter the option\nmatching loop even when foptsize sums to zero, which matches packets\nwith no TCP options where ctx->optp is NULL:\n\n Oops: general protection fault\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)\n Call Trace:\n  nf_osf_match (net/netfilter/nfnetlink_osf.c:227)\n  xt_osf_match_packet (net/netfilter/xt_osf.c:32)\n  ipt_do_table (net/ipv4/netfilter/ip_tables.c:293)\n  nf_hook_slow (net/netfilter/core.c:623)\n  ip_local_deliver (net/ipv4/ip_input.c:262)\n  ip_rcv (net/ipv4/ip_input.c:573)\n\nAdditionally, an MSS option (kind=2) with length < 4 causes\nout-of-bounds reads when nf_osf_match_one() unconditionally accesses\noptp[2] and optp[3] for MSS value extraction.  While RFC 9293\nsection 3.2 specifies that the MSS option is always exactly 4\nbytes (Kind=2, Length=4), the check uses \"< 4\" rather than\n\"!= 4\" because lengths greater than 4 do not cause memory\nsafety issues -- the buffer is guaranteed to be at least\nfoptsize bytes by the ctx->optsize == foptsize check.\n\nReject fingerprints where any option has zero length, or where an MSS\noption has length less than 4, at add time rather than trusting these\nvalues in the packet matching hot path.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-03-26 11:16:19","updated_at":"2026-04-18 09:16:23"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6","name":"https://git.kernel.org/stable/c/4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dbdfaae9609629a9569362e3b8f33d0a20fd783c","name":"https://git.kernel.org/stable/c/dbdfaae9609629a9569362e3b8f33d0a20fd783c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ec8bf0571b142f29dc0b68ae2ac3952f7a464b38","name":"https://git.kernel.org/stable/c/ec8bf0571b142f29dc0b68ae2ac3952f7a464b38","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/aa0574182c46963c3cdb8cde46ec93aca21100d8","name":"https://git.kernel.org/stable/c/aa0574182c46963c3cdb8cde46ec93aca21100d8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e9cf17b91e733fec725ebcc0b3098bc5ccd505e0","name":"https://git.kernel.org/stable/c/e9cf17b91e733fec725ebcc0b3098bc5ccd505e0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3c11b5c2436a3a5b450612ab160e3a525b28cfb5","name":"https://git.kernel.org/stable/c/3c11b5c2436a3a5b450612ab160e3a525b28cfb5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/224f4678812e1a7bc8341bcb666773a0aec5ea6f","name":"https://git.kernel.org/stable/c/224f4678812e1a7bc8341bcb666773a0aec5ea6f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3932620c04c2938c93c0890c225960d3d34ba355","name":"https://git.kernel.org/stable/c/3932620c04c2938c93c0890c225960d3d34ba355","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-23397","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23397","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 e9cf17b91e733fec725ebcc0b3098bc5ccd505e0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 3c11b5c2436a3a5b450612ab160e3a525b28cfb5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 aa0574182c46963c3cdb8cde46ec93aca21100d8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 224f4678812e1a7bc8341bcb666773a0aec5ea6f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.203 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.167 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.130 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.78 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.20 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.10 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"23397","cve":"CVE-2026-23397","epss":"0.000320000","percentile":"0.090980000","score_date":"2026-04-18","updated_at":"2026-04-19 00:10:43"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/netfilter/nfnetlink_osf.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"e9cf17b91e733fec725ebcc0b3098bc5ccd505e0","status":"affected","version":"11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384","versionType":"git"},{"lessThan":"3c11b5c2436a3a5b450612ab160e3a525b28cfb5","status":"affected","version":"11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384","versionType":"git"},{"lessThan":"aa0574182c46963c3cdb8cde46ec93aca21100d8","status":"affected","version":"11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384","versionType":"git"},{"lessThan":"224f4678812e1a7bc8341bcb666773a0aec5ea6f","status":"affected","version":"11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384","versionType":"git"},{"lessThan":"ec8bf0571b142f29dc0b68ae2ac3952f7a464b38","status":"affected","version":"11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384","versionType":"git"},{"lessThan":"3932620c04c2938c93c0890c225960d3d34ba355","status":"affected","version":"11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384","versionType":"git"},{"lessThan":"4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6","status":"affected","version":"11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384","versionType":"git"},{"lessThan":"dbdfaae9609629a9569362e3b8f33d0a20fd783c","status":"affected","version":"11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/netfilter/nfnetlink_osf.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.31"},{"lessThan":"2.6.31","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.253","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.203","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.167","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.130","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.78","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.20","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.10","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.0","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.253","versionStartIncluding":"2.6.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.203","versionStartIncluding":"2.6.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.167","versionStartIncluding":"2.6.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.130","versionStartIncluding":"2.6.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.78","versionStartIncluding":"2.6.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.20","versionStartIncluding":"2.6.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.10","versionStartIncluding":"2.6.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0","versionStartIncluding":"2.6.31","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfnetlink_osf: validate individual option lengths in fingerprints\n\nnfnl_osf_add_callback() validates opt_num bounds and string\nNUL-termination but does not check individual option length fields.\nA zero-length option causes nf_osf_match_one() to enter the option\nmatching loop even when foptsize sums to zero, which matches packets\nwith no TCP options where ctx->optp is NULL:\n\n Oops: general protection fault\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)\n Call Trace:\n  nf_osf_match (net/netfilter/nfnetlink_osf.c:227)\n  xt_osf_match_packet (net/netfilter/xt_osf.c:32)\n  ipt_do_table (net/ipv4/netfilter/ip_tables.c:293)\n  nf_hook_slow (net/netfilter/core.c:623)\n  ip_local_deliver (net/ipv4/ip_input.c:262)\n  ip_rcv (net/ipv4/ip_input.c:573)\n\nAdditionally, an MSS option (kind=2) with length < 4 causes\nout-of-bounds reads when nf_osf_match_one() unconditionally accesses\noptp[2] and optp[3] for MSS value extraction.  While RFC 9293\nsection 3.2 specifies that the MSS option is always exactly 4\nbytes (Kind=2, Length=4), the check uses \"< 4\" rather than\n\"!= 4\" because lengths greater than 4 do not cause memory\nsafety issues -- the buffer is guaranteed to be at least\nfoptsize bytes by the ctx->optsize == foptsize check.\n\nReject fingerprints where any option has zero length, or where an MSS\noption has length less than 4, at add time rather than trusting these\nvalues in the packet matching hot path."}],"providerMetadata":{"dateUpdated":"2026-04-18T08:58:32.483Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/e9cf17b91e733fec725ebcc0b3098bc5ccd505e0"},{"url":"https://git.kernel.org/stable/c/3c11b5c2436a3a5b450612ab160e3a525b28cfb5"},{"url":"https://git.kernel.org/stable/c/aa0574182c46963c3cdb8cde46ec93aca21100d8"},{"url":"https://git.kernel.org/stable/c/224f4678812e1a7bc8341bcb666773a0aec5ea6f"},{"url":"https://git.kernel.org/stable/c/ec8bf0571b142f29dc0b68ae2ac3952f7a464b38"},{"url":"https://git.kernel.org/stable/c/3932620c04c2938c93c0890c225960d3d34ba355"},{"url":"https://git.kernel.org/stable/c/4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6"},{"url":"https://git.kernel.org/stable/c/dbdfaae9609629a9569362e3b8f33d0a20fd783c"}],"title":"nfnetlink_osf: validate individual option lengths in fingerprints","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-23397","datePublished":"2026-03-26T10:22:49.954Z","dateReserved":"2026-01-13T15:37:46.011Z","dateUpdated":"2026-04-18T08:58:32.483Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-03-26 11:16:19","lastModifiedDate":"2026-04-18 09:16:23","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"23397","Ordinal":"1","Title":"nfnetlink_osf: validate individual option lengths in fingerprint","CVE":"CVE-2026-23397","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"23397","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfnetlink_osf: validate individual option lengths in fingerprints\n\nnfnl_osf_add_callback() validates opt_num bounds and string\nNUL-termination but does not check individual option length fields.\nA zero-length option causes nf_osf_match_one() to enter the option\nmatching loop even when foptsize sums to zero, which matches packets\nwith no TCP options where ctx->optp is NULL:\n\n Oops: general protection fault\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)\n Call Trace:\n  nf_osf_match (net/netfilter/nfnetlink_osf.c:227)\n  xt_osf_match_packet (net/netfilter/xt_osf.c:32)\n  ipt_do_table (net/ipv4/netfilter/ip_tables.c:293)\n  nf_hook_slow (net/netfilter/core.c:623)\n  ip_local_deliver (net/ipv4/ip_input.c:262)\n  ip_rcv (net/ipv4/ip_input.c:573)\n\nAdditionally, an MSS option (kind=2) with length < 4 causes\nout-of-bounds reads when nf_osf_match_one() unconditionally accesses\noptp[2] and optp[3] for MSS value extraction.  While RFC 9293\nsection 3.2 specifies that the MSS option is always exactly 4\nbytes (Kind=2, Length=4), the check uses \"< 4\" rather than\n\"!= 4\" because lengths greater than 4 do not cause memory\nsafety issues -- the buffer is guaranteed to be at least\nfoptsize bytes by the ctx->optsize == foptsize check.\n\nReject fingerprints where any option has zero length, or where an MSS\noption has length less than 4, at add time rather than trusting these\nvalues in the packet matching hot path.","Type":"Description","Title":"nfnetlink_osf: validate individual option lengths in fingerprint"}]}}}