{"id":"CVE-2026-64554","title":"kernel: netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment() (CVE-2026-64554)","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 skb…","severity":"high","cvss":7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"vendor","cwe":"CWE-825","vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 9","enterprise_linux 6"],"published":"2026-07-27","updated":"2026-10-23","sourceUpdated":"2026-10-23T11:18:43+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64554.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64554.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-64554"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2507747"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64554"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64554"},{"url":"https://lore.kernel.org/linux-cve-announce/2026072738-CVE-2026-64554-e179@gregkh/T"},{"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":["csaf","vex","red-hat","cve.org"],"epss":0.00256,"epssPercentile":0.17127,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:42:31.205965Z"},"scores":{"vendor":7,"cna":8.8},"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## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 6 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64554.json)\n\n**kernel: netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()** — rated Moderate by Red Hat. Released 2026-07-27, updated 2026-10-23.\n\nAffected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 9\n- Red Hat Enterprise Linux 6\n\nNo fix planned:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 9\n\nNot affected:\n\n- Red Hat Enterprise Linux 7\n- Red Hat Enterprise Linux 8\n\n## Remediation\n\nAffected","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":228071,"id":"CVE-2026-64554","ts":1792758068772,"field":"cvss","old":"8.8","new":"7"}]}