{"id":"CVE-2026-64554","title":"netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()\n\nbr_ip6_fragment() gets prevhdr, a pointer into the skb head, from\nip6_find_1stfragopt(), then calls s…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 8c10778ec674b67a07ea042fcba64270f3f38a5a","Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 2731efa6364e47934c96eb69e01ea131e8af8030","Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 00c06ef8c018493943891a7d0ca82b71b24f3180","Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < c141f69d0a0fb16964dbc293650047e69bda8af7","Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < f2e6596d10783557aeb9668da2a3b4d19deb2001","Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 1c4f67c89fd27c4df4c70b135c2c59627698b3c0","Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 4ac981a8b7ce7aec99a52d08f8a8953e8e120067","Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d","Linux 5.3"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:42:31.205965Z"},"published":"2026-07-27","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:52:52.280Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64554","references":[{"url":"https://git.kernel.org/stable/c/8c10778ec674b67a07ea042fcba64270f3f38a5a"},{"url":"https://git.kernel.org/stable/c/2731efa6364e47934c96eb69e01ea131e8af8030"},{"url":"https://git.kernel.org/stable/c/00c06ef8c018493943891a7d0ca82b71b24f3180"},{"url":"https://git.kernel.org/stable/c/c141f69d0a0fb16964dbc293650047e69bda8af7"},{"url":"https://git.kernel.org/stable/c/f2e6596d10783557aeb9668da2a3b4d19deb2001"},{"url":"https://git.kernel.org/stable/c/1c4f67c89fd27c4df4c70b135c2c59627698b3c0"},{"url":"https://git.kernel.org/stable/c/4ac981a8b7ce7aec99a52d08f8a8953e8e120067"},{"url":"https://git.kernel.org/stable/c/86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d"}],"tags":["cve.org"],"epss":0.00255,"epssPercentile":0.15954,"ingestedAt":"2026-10-16T17:24:46.832Z","slug":"CVE-2026-64554","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()\n\nbr_ip6_fragment() gets prevhdr, a pointer into the skb head, from\nip6_find_1stfragopt(), then calls skb_checksum_help().  For a cloned skb\nskb_checksum_help() reallocates the head via pskb_expand_head(), leaving\nprevhdr dangling.  It is later dereferenced in ip6_frag_next(), causing a\nuse-after-free write.\n\nSave prevhdr's offset before skb_checksum_help() and recompute it after,\nlike commit ef0efcd3bd3f (\"ipv6: Fix dangling pointer when ipv6\nfragment\").\n\n  BUG: KASAN: slab-use-after-free in ip6_frag_next (net/ipv6/ip6_output.c:857)\n  Write of size 1 at addr ffff888013ff5016 by task exploit/141\n  Call Trace:\n   ...\n   kasan_report (mm/kasan/report.c:595)\n   ip6_frag_next (net/ipv6/ip6_output.c:857)\n   br_ip6_fragment (net/ipv6/netfilter.c:212)\n   nf_ct_bridge_post (net/bridge/netfilter/nf_conntrack_bridge.c:407)\n   nf_hook_slow (net/netfilter/core.c:619)\n   br_forward_finish (net/bridge/br_forward.c:66)\n   __br_forward (net/bridge/br_forward.c:115)\n   maybe_deliver (net/bridge/br_forward.c:191)\n   br_flood (net/bridge/br_forward.c:245)\n   br_handle_frame_finish (net/bridge/br_input.c:229)\n   br_handle_frame (net/bridge/br_input.c:442)\n   ...\n   packet_sendmsg (net/packet/af_packet.c:3114)\n   ...\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n  Kernel panic - not syncing: Fatal exception in interrupt\n\n## Affected\n\n- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 8c10778ec674b67a07ea042fcba64270f3f38a5a`\n- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 2731efa6364e47934c96eb69e01ea131e8af8030`\n- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 00c06ef8c018493943891a7d0ca82b71b24f3180`\n- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < c141f69d0a0fb16964dbc293650047e69bda8af7`\n- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < f2e6596d10783557aeb9668da2a3b4d19deb2001`\n- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 1c4f67c89fd27c4df4c70b135c2c59627698b3c0`\n- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 4ac981a8b7ce7aec99a52d08f8a8953e8e120067`\n- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d`\n- `Linux 5.3`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}