{"id":"CVE-2026-72250","title":"netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag\n\nnf_ct_frag6_reasm() slides the packet head forward to drop the IPv6\nfragment header and th…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 6e8cd710ca35c576f5f2e5a396047c9ac61f75e5","Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 2a95ec21824a8ad81ad660b12231456fc0ac9830","Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < bbcdef2061b170af45702ce6b359c02c12acfc94","Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58","Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 53ef70a315420ed31581d38343684b3bf9a3c76d","Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < a58230f3a7c4f6c3261786bc1efb72c42e68cd25","Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 00bdce2fda7e430d24cfbc96764a1b96deb31f82","Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9","Linux 2.6.15"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:45:08.646891Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:13.023Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72250","references":[{"url":"https://git.kernel.org/stable/c/6e8cd710ca35c576f5f2e5a396047c9ac61f75e5"},{"url":"https://git.kernel.org/stable/c/2a95ec21824a8ad81ad660b12231456fc0ac9830"},{"url":"https://git.kernel.org/stable/c/bbcdef2061b170af45702ce6b359c02c12acfc94"},{"url":"https://git.kernel.org/stable/c/cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58"},{"url":"https://git.kernel.org/stable/c/53ef70a315420ed31581d38343684b3bf9a3c76d"},{"url":"https://git.kernel.org/stable/c/a58230f3a7c4f6c3261786bc1efb72c42e68cd25"},{"url":"https://git.kernel.org/stable/c/00bdce2fda7e430d24cfbc96764a1b96deb31f82"},{"url":"https://git.kernel.org/stable/c/3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9"}],"tags":["cve.org"],"epss":0.00169,"epssPercentile":0.05793,"ingestedAt":"2026-10-16T19:46:24.415Z","slug":"CVE-2026-72250","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag\n\nnf_ct_frag6_reasm() slides the packet head forward to drop the IPv6\nfragment header and then unconditionally advances skb->mac_header:\n\n\tskb->mac_header += sizeof(struct frag_hdr);\n\nOn the NF_INET_LOCAL_OUT defrag path the skb has no link-layer header\nyet, so skb->mac_header is still the \"not set\" sentinel (u16)~0U. Adding\nsizeof(struct frag_hdr) wraps it to a small value (0xffff + 8 == 7),\nafter which skb_mac_header_was_set() wrongly reports a MAC header is\npresent and skb_mac_header() points into the headroom.\n\nThe reassembler has done this unconditional add since it was introduced;\nit was harmless while mac_header was a bare pointer, but wrong once\nmac_header became a u16 offset whose unset state is the ~0U sentinel\ntested by skb_mac_header_was_set(). The sibling net/ipv6/reassembly.c\ndoes the same relocation and does guard the adjustment; mirror the\nguard here.\n\n## Affected\n\n- `Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 6e8cd710ca35c576f5f2e5a396047c9ac61f75e5`\n- `Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 2a95ec21824a8ad81ad660b12231456fc0ac9830`\n- `Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < bbcdef2061b170af45702ce6b359c02c12acfc94`\n- `Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58`\n- `Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 53ef70a315420ed31581d38343684b3bf9a3c76d`\n- `Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < a58230f3a7c4f6c3261786bc1efb72c42e68cd25`\n- `Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 00bdce2fda7e430d24cfbc96764a1b96deb31f82`\n- `Linux >= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9`\n- `Linux 2.6.15`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}