{"schema":"threatline.record/2","record":{"id":"CVE-2026-99074","aliases":[],"summary":"ipv4: stop PMTU walk when nexthop group shrinks","details":"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.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","source_modified_at":"2026-10-23T12:23:17.866Z","fetched_at":"2026-10-23T18:42:43.628194Z","product":"Linux","vendor":"Linux","versions":[{"version":"3bed2abab4a682d426624ce9add9d7b6d475d4e4","lessThan":"7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a","status":"affected","versionType":"git"},{"version":"7f5005457b3072fe1ddf15bfef869f2a1d98e05e","lessThan":"c60d17d6dd61adc761ac6f65a008fefbc54cbf87","status":"affected","versionType":"git"},{"version":"7d3f3b4367f315a61fc615e3138f3d320da8c466","lessThan":"c6d670ac656badfd0e15355e07a13a6bdf3b69fd","status":"affected","versionType":"git"},{"version":"7d3f3b4367f315a61fc615e3138f3d320da8c466","lessThan":"f27483f9975b5065ff67054cc7eb8edac6083488","status":"affected","versionType":"git"},{"version":"7d3f3b4367f315a61fc615e3138f3d320da8c466","lessThan":"6619e01855e65ef35723685a557e3eb106f4ecf5","status":"affected","versionType":"git"},{"version":"fc07a232326a623d0be482e307c08ea7049c2846","status":"affected","versionType":"git"},{"version":"b1f7bdee5750d6cbb9497140cd6582abc5fdcb9e","status":"affected","versionType":"git"},{"version":"6.6.79","lessThan":"6.6.160","status":"affected","versionType":"semver"},{"version":"6.12.16","lessThan":"6.12.113","status":"affected","versionType":"semver"},{"version":"5.15.179","lessThan":"5.16","status":"affected","versionType":"semver"},{"version":"6.1.129","lessThan":"6.2","status":"affected","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","source_modified_at":"2026-10-23T12:23:17.866Z","fetched_at":"2026-10-23T18:42:43.628194Z","product":"Linux","vendor":"Linux","versions":[{"version":"6.13","status":"affected"},{"version":"0","lessThan":"6.13","status":"unaffected","versionType":"semver"},{"version":"6.6.160","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.113","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.57","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.11","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","source_modified_at":"2026-10-23T12:23:17.866Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","source_modified_at":"2026-10-23T12:23:17.866Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"6619e01855e65ef35723685a557e3eb106f4ecf5","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","source_modified_at":"2026-10-23T12:23:17.866Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"6.6.160","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","source_modified_at":"2026-10-23T12:23:17.866Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"6.12.113","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","source_modified_at":"2026-10-23T12:23:17.866Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"5.16","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","source_modified_at":"2026-10-23T12:23:17.866Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"6.2","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":null,"percentile":null,"score_date":null},"published_at":"2026-10-23T12:23:17.866Z","modified_at":"2026-10-23T12:23:17.866Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-99074","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23T12:23:17.866Z"}],"sources":["CVE List"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/c60d17d6dd61adc761ac6f65a008fefbc54cbf87"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/c6d670ac656badfd0e15355e07a13a6bdf3b69fd"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/f27483f9975b5065ff67054cc7eb8edac6083488"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/6619e01855e65ef35723685a557e3eb106f4ecf5"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-23T12:23:17.866Z","content_hash":"79b107ab006194ddd1a76b3a3e9bfbe75e12e244a5c027b6fc41e409a901845e"}}