{"api_version":"1","generated_at":"2026-10-27T04:32:01+00:00","cve":"CVE-2026-99074","urls":{"html":"https://cve.report/CVE-2026-99074","api":"https://cve.report/api/cve/CVE-2026-99074.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99074","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99074"},"summary":{"title":"ipv4: stop PMTU walk when nexthop group shrinks","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: stop PMTU walk when nexthop group shrinks\n\nCommit 7d3f3b4367f3 (\"net: ipv4: Cache pmtu for all packet paths if\nmultipath enabled\") made __ip_rt_update_pmtu() update every path.\n\nFor nexthop objects, fib_info_num_path() and fib_info_nhc()\nindependently load nh->nh_grp.  RCU protects each group's lifetime but\ndoes not make the loads observe the same group.  If replacement shrinks\nthe group after the loop accepts an index, fib_info_nhc() returns NULL\nand update_or_create_fnhe() dereferences it.\n\nA deterministic probe only widened the existing window between the real\noperations.  On v7.2, an RTM_NEWNEXTHOP replacement published a\none-member group after the PMTU reader accepted index 1 from a two-member\ngroup, producing:\n\n  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n  RIP: update_or_create_fnhe+0x45/0x15b0\n\nStop when the indexed path is absent.  Groups are dense, so no later\nindex exists in that snapshot.  The same real-writer window completed\n114,423 PMTU iterations without an oops with this check.  A reproducer\nis available on request.\n\nReplacement requires CAP_NET_ADMIN in the network namespace.  Where\nunprivileged user namespaces are permitted, a local user can obtain it\nin a new user and network namespace.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-23 13:17:31","updated_at":"2026-10-23 13:17:31"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/f27483f9975b5065ff67054cc7eb8edac6083488","name":"https://git.kernel.org/stable/c/f27483f9975b5065ff67054cc7eb8edac6083488","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6619e01855e65ef35723685a557e3eb106f4ecf5","name":"https://git.kernel.org/stable/c/6619e01855e65ef35723685a557e3eb106f4ecf5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a","name":"https://git.kernel.org/stable/c/7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c6d670ac656badfd0e15355e07a13a6bdf3b69fd","name":"https://git.kernel.org/stable/c/c6d670ac656badfd0e15355e07a13a6bdf3b69fd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c60d17d6dd61adc761ac6f65a008fefbc54cbf87","name":"https://git.kernel.org/stable/c/c60d17d6dd61adc761ac6f65a008fefbc54cbf87","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99074","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3bed2abab4a682d426624ce9add9d7b6d475d4e4 7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7f5005457b3072fe1ddf15bfef869f2a1d98e05e c60d17d6dd61adc761ac6f65a008fefbc54cbf87 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7d3f3b4367f315a61fc615e3138f3d320da8c466 c6d670ac656badfd0e15355e07a13a6bdf3b69fd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7d3f3b4367f315a61fc615e3138f3d320da8c466 f27483f9975b5065ff67054cc7eb8edac6083488 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7d3f3b4367f315a61fc615e3138f3d320da8c466 6619e01855e65ef35723685a557e3eb106f4ecf5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fc07a232326a623d0be482e307c08ea7049c2846 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b1f7bdee5750d6cbb9497140cd6582abc5fdcb9e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.79 6.6.160 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.16 6.12.113 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.15.179 5.16 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.129 6.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.13","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.13 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.160 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.113 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.57 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.11 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/ipv4/route.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a","status":"affected","version":"3bed2abab4a682d426624ce9add9d7b6d475d4e4","versionType":"git"},{"lessThan":"c60d17d6dd61adc761ac6f65a008fefbc54cbf87","status":"affected","version":"7f5005457b3072fe1ddf15bfef869f2a1d98e05e","versionType":"git"},{"lessThan":"c6d670ac656badfd0e15355e07a13a6bdf3b69fd","status":"affected","version":"7d3f3b4367f315a61fc615e3138f3d320da8c466","versionType":"git"},{"lessThan":"f27483f9975b5065ff67054cc7eb8edac6083488","status":"affected","version":"7d3f3b4367f315a61fc615e3138f3d320da8c466","versionType":"git"},{"lessThan":"6619e01855e65ef35723685a557e3eb106f4ecf5","status":"affected","version":"7d3f3b4367f315a61fc615e3138f3d320da8c466","versionType":"git"},{"status":"affected","version":"fc07a232326a623d0be482e307c08ea7049c2846","versionType":"git"},{"status":"affected","version":"b1f7bdee5750d6cbb9497140cd6582abc5fdcb9e","versionType":"git"},{"lessThan":"6.6.160","status":"affected","version":"6.6.79","versionType":"semver"},{"lessThan":"6.12.113","status":"affected","version":"6.12.16","versionType":"semver"},{"lessThan":"5.16","status":"affected","version":"5.15.179","versionType":"semver"},{"lessThan":"6.2","status":"affected","version":"6.1.129","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/ipv4/route.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.13"},{"lessThan":"6.13","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.160","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.113","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.57","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.160","versionStartIncluding":"6.6.79","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.113","versionStartIncluding":"6.12.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.57","versionStartIncluding":"6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.11","versionStartIncluding":"6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.179","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.129","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: stop PMTU walk when nexthop group shrinks\n\nCommit 7d3f3b4367f3 (\"net: ipv4: Cache pmtu for all packet paths if\nmultipath enabled\") made __ip_rt_update_pmtu() update every path.\n\nFor nexthop objects, fib_info_num_path() and fib_info_nhc()\nindependently load nh->nh_grp.  RCU protects each group's lifetime but\ndoes not make the loads observe the same group.  If replacement shrinks\nthe group after the loop accepts an index, fib_info_nhc() returns NULL\nand update_or_create_fnhe() dereferences it.\n\nA deterministic probe only widened the existing window between the real\noperations.  On v7.2, an RTM_NEWNEXTHOP replacement published a\none-member group after the PMTU reader accepted index 1 from a two-member\ngroup, producing:\n\n  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n  RIP: update_or_create_fnhe+0x45/0x15b0\n\nStop when the indexed path is absent.  Groups are dense, so no later\nindex exists in that snapshot.  The same real-writer window completed\n114,423 PMTU iterations without an oops with this check.  A reproducer\nis available on request.\n\nReplacement requires CAP_NET_ADMIN in the network namespace.  Where\nunprivileged user namespaces are permitted, a local user can obtain it\nin a new user and network namespace."}],"providerMetadata":{"dateUpdated":"2026-10-23T12:23:17.866Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a"},{"url":"https://git.kernel.org/stable/c/c60d17d6dd61adc761ac6f65a008fefbc54cbf87"},{"url":"https://git.kernel.org/stable/c/c6d670ac656badfd0e15355e07a13a6bdf3b69fd"},{"url":"https://git.kernel.org/stable/c/f27483f9975b5065ff67054cc7eb8edac6083488"},{"url":"https://git.kernel.org/stable/c/6619e01855e65ef35723685a557e3eb106f4ecf5"}],"title":"ipv4: stop PMTU walk when nexthop group shrinks","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99074","datePublished":"2026-10-23T12:23:17.866Z","dateReserved":"2026-09-25T10:25:14.389Z","dateUpdated":"2026-10-23T12:23:17.866Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-23 13:17:31","lastModifiedDate":"2026-10-23 13:17:31","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"99074","Ordinal":"1","Title":"ipv4: stop PMTU walk when nexthop group shrinks","CVE":"CVE-2026-99074","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99074","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: stop PMTU walk when nexthop group shrinks\n\nCommit 7d3f3b4367f3 (\"net: ipv4: Cache pmtu for all packet paths if\nmultipath enabled\") made __ip_rt_update_pmtu() update every path.\n\nFor nexthop objects, fib_info_num_path() and fib_info_nhc()\nindependently load nh->nh_grp.  RCU protects each group's lifetime but\ndoes not make the loads observe the same group.  If replacement shrinks\nthe group after the loop accepts an index, fib_info_nhc() returns NULL\nand update_or_create_fnhe() dereferences it.\n\nA deterministic probe only widened the existing window between the real\noperations.  On v7.2, an RTM_NEWNEXTHOP replacement published a\none-member group after the PMTU reader accepted index 1 from a two-member\ngroup, producing:\n\n  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n  RIP: update_or_create_fnhe+0x45/0x15b0\n\nStop when the indexed path is absent.  Groups are dense, so no later\nindex exists in that snapshot.  The same real-writer window completed\n114,423 PMTU iterations without an oops with this check.  A reproducer\nis available on request.\n\nReplacement requires CAP_NET_ADMIN in the network namespace.  Where\nunprivileged user namespaces are permitted, a local user can obtain it\nin a new user and network namespace.","Type":"Description","Title":"ipv4: stop PMTU walk when nexthop group shrinks"}]}}}