{"api_version":"1","generated_at":"2026-08-02T22:38:14+00:00","cve":"CVE-2026-64538","urls":{"html":"https://cve.report/CVE-2026-64538","api":"https://cve.report/api/cve/CVE-2026-64538.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64538","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64538"},"summary":{"title":"ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Fix null-ptr-deref in fib6_nh_mtu_change().\n\nfib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg->dev) and\ndereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown()\nclears dev->ip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has\nreleased tb6_lock, so the RA-driven MTU walk can observe a NULL idev and\noops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(),\nbut this re-fetch is unguarded; nexthop-backed routes survive\naddrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is\nnulled.\n\nReturn 0 when idev is NULL, matching rt6_mtu_change_route() and the\nfib6_mtu() fix in commit 5ad509c1fdad (\"ipv6: Fix null-ptr-deref in\nfib6_mtu().\").\n\n  Oops: general protection fault, ... KASAN: null-ptr-deref in range\n        [0x00000000000002a8-0x00000000000002af]\n  RIP: 0010:fib6_nh_mtu_change+0x203/0x990\n   rt6_mtu_change_route+0x141/0x1d0\n   __fib6_clean_all+0xd0/0x160\n   rt6_mtu_change+0xb4/0x100\n   ndisc_router_discovery+0x24b5/0x2cb0\n   icmpv6_rcv+0x12e9/0x1710\n   ipv6_rcv+0x39b/0x410","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-27 21:17:06","updated_at":"2026-07-27 21:17:06"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5","name":"https://git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051a","name":"https://git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4f","name":"https://git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905","name":"https://git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33","name":"https://git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967","name":"https://git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9","name":"https://git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37b","name":"https://git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64538","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64538","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e d08d019f2f43a6f9a71e81868bbc326b3afaf37b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e 1451deca9896957159f0666520a792c1b861af4f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e b2c70dd3326809429b709a9c7e9220d29923051a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e 302d57ed7872838b40e56a868fb4c7da7da606e9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.212 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.178 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.145 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.97 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.40 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"64538","cve":"CVE-2026-64538","epss":"0.001760000","percentile":"0.074350000","score_date":"2026-07-29","updated_at":"2026-07-30 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the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Fix null-ptr-deref in fib6_nh_mtu_change().\n\nfib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg->dev) and\ndereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown()\nclears dev->ip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has\nreleased tb6_lock, so the RA-driven MTU walk can observe a NULL idev and\noops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(),\nbut this re-fetch is unguarded; nexthop-backed routes survive\naddrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is\nnulled.\n\nReturn 0 when idev is NULL, matching rt6_mtu_change_route() and the\nfib6_mtu() fix in commit 5ad509c1fdad (\"ipv6: Fix null-ptr-deref in\nfib6_mtu().\").\n\n  Oops: general protection fault, ... KASAN: null-ptr-deref in range\n        [0x00000000000002a8-0x00000000000002af]\n  RIP: 0010:fib6_nh_mtu_change+0x203/0x990\n   rt6_mtu_change_route+0x141/0x1d0\n   __fib6_clean_all+0xd0/0x160\n   rt6_mtu_change+0xb4/0x100\n   ndisc_router_discovery+0x24b5/0x2cb0\n   icmpv6_rcv+0x12e9/0x1710\n   ipv6_rcv+0x39b/0x410"}],"providerMetadata":{"dateUpdated":"2026-07-27T20:10:32.779Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37b"},{"url":"https://git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4f"},{"url":"https://git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051a"},{"url":"https://git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9"},{"url":"https://git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5"},{"url":"https://git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33"},{"url":"https://git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967"},{"url":"https://git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905"}],"title":"ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64538","datePublished":"2026-07-27T20:10:32.779Z","dateReserved":"2026-07-19T15:36:31.795Z","dateUpdated":"2026-07-27T20:10:32.779Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-27 21:17:06","lastModifiedDate":"2026-07-27 21:17:06","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64538","Ordinal":"1","Title":"ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().","CVE":"CVE-2026-64538","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64538","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Fix null-ptr-deref in fib6_nh_mtu_change().\n\nfib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg->dev) and\ndereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown()\nclears dev->ip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has\nreleased tb6_lock, so the RA-driven MTU walk can observe a NULL idev and\noops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(),\nbut this re-fetch is unguarded; nexthop-backed routes survive\naddrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is\nnulled.\n\nReturn 0 when idev is NULL, matching rt6_mtu_change_route() and the\nfib6_mtu() fix in commit 5ad509c1fdad (\"ipv6: Fix null-ptr-deref in\nfib6_mtu().\").\n\n  Oops: general protection fault, ... KASAN: null-ptr-deref in range\n        [0x00000000000002a8-0x00000000000002af]\n  RIP: 0010:fib6_nh_mtu_change+0x203/0x990\n   rt6_mtu_change_route+0x141/0x1d0\n   __fib6_clean_all+0xd0/0x160\n   rt6_mtu_change+0xb4/0x100\n   ndisc_router_discovery+0x24b5/0x2cb0\n   icmpv6_rcv+0x12e9/0x1710\n   ipv6_rcv+0x39b/0x410","Type":"Description","Title":"ipv6: Fix null-ptr-deref in fib6_nh_mtu_change()."}]}}}