{"api_version":"1","generated_at":"2026-08-18T13:36:25+00:00","cve":"CVE-2026-72250","urls":{"html":"https://cve.report/CVE-2026-72250","api":"https://cve.report/api/cve/CVE-2026-72250.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72250","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72250"},"summary":{"title":"netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag","description":"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 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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:21:52","updated_at":"2026-08-17 06:18:27"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/a58230f3a7c4f6c3261786bc1efb72c42e68cd25","name":"https://git.kernel.org/stable/c/a58230f3a7c4f6c3261786bc1efb72c42e68cd25","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/53ef70a315420ed31581d38343684b3bf9a3c76d","name":"https://git.kernel.org/stable/c/53ef70a315420ed31581d38343684b3bf9a3c76d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6e8cd710ca35c576f5f2e5a396047c9ac61f75e5","name":"https://git.kernel.org/stable/c/6e8cd710ca35c576f5f2e5a396047c9ac61f75e5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9","name":"https://git.kernel.org/stable/c/3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58","name":"https://git.kernel.org/stable/c/cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/00bdce2fda7e430d24cfbc96764a1b96deb31f82","name":"https://git.kernel.org/stable/c/00bdce2fda7e430d24cfbc96764a1b96deb31f82","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/bbcdef2061b170af45702ce6b359c02c12acfc94","name":"https://git.kernel.org/stable/c/bbcdef2061b170af45702ce6b359c02c12acfc94","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2a95ec21824a8ad81ad660b12231456fc0ac9830","name":"https://git.kernel.org/stable/c/2a95ec21824a8ad81ad660b12231456fc0ac9830","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-72250","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72250","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 6e8cd710ca35c576f5f2e5a396047c9ac61f75e5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 2a95ec21824a8ad81ad660b12231456fc0ac9830 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 bbcdef2061b170af45702ce6b359c02c12acfc94 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58 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 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"72250","cve":"CVE-2026-72250","epss":"0.001640000","percentile":"0.060850000","score_date":"2026-08-17","updated_at":"2026-08-18 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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."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The bug triggers only when nf_ct_frag6_reasm() runs on NF_INET_LOCAL_OUT with skb->mac_header still unset (~0U). That requires injecting pre-fragmented IPv6 into the local output path (e.g., AF_INET6 SOCK_RAW), not standard remotely received PRE_ROUTING traffic where mac_header is already valid and the adjustment is correct.\nAC:L - An attacker who can send raw IPv6 fragments can reliably complete conntrack reassembly by crafting matching fragment ID/source/destination tuples. nf_defrag_ipv6 is enabled automatically whenever IPv6 connection tracking is in use (typical on nftables/iptables hosts), so no rare race or admin-only timing is needed.\nPR:L - Triggering handcrafted IPv6 fragments requires CAP_NET_RAW. On systems with unprivileged user namespaces, a local user can obtain CAP_NET_RAW (and CAP_NET_ADMIN for conntrack) via unshare -Urn, so required privileges are Low rather than High root-only access.\nUI:N - Exploitation requires only attacker-controlled fragmented IPv6 traffic and an active conntrack defrag path; it does not depend on any victim user action such as opening files, mounting filesystems, or clicking links.\nS:U - Impact is skb metadata corruption within the kernel network stack in the same security domain. It does not inherently cross VM, container runtime, or IOMMU boundaries without separate privilege-escalation exploitation.\nC:H - Adding sizeof(frag_hdr) to the unset mac_header sentinel wraps to a small offset, so skb_mac_header_was_set() becomes true and skb_mac_header() points into skb headroom. Downstream netfilter/nft L2 helpers can then perform out-of-bounds reads, leaking stale kernel data from headroom.\nI:H - The bogus mac_header and inflated skb_mac_header_len() misdirect later L2 header access and nft payload/meta write paths to incorrect offsets in skb headroom or packet data, enabling memory corruption that can be leveraged for arbitrary kernel writes or control-flow hijacking.\nA:H - Corrupted skb header state can cause kernel oops, panic, or fatal faults when subsequent LOCAL_OUT, netfilter, or output routines use the invalid MAC header pointer, and the associated memory corruption can crash the system even without full exploit development."}]}],"providerMetadata":{"dateUpdated":"2026-08-17T05:42:02.183Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}],"title":"netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72250","datePublished":"2026-08-15T05:54:39.134Z","dateReserved":"2026-08-09T03:40:39.915Z","dateUpdated":"2026-08-17T05:42:02.183Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:21:52","lastModifiedDate":"2026-08-17 06:18:27","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72250","Ordinal":"1","Title":"netfilter: nf_conntrack_reasm: guard mac_header adjustment after","CVE":"CVE-2026-72250","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72250","Ordinal":"1","NoteData":"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 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.","Type":"Description","Title":"netfilter: nf_conntrack_reasm: guard mac_header adjustment after"}]}}}