{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-80731", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.789Z", "datePublished": "2026-09-03T08:21:48.924Z", "dateUpdated": "2026-09-04T04:58:17.510Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-04T04:58:17.510Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: remove CAP_SYS_RAWIO zero-padding in dev_validate_header\n\ndev_validate_header() reads dev->hard_header_len directly when\nzero-padding short link layer headers for CAP_SYS_RAWIO holders:\n\n if (capable(CAP_SYS_RAWIO)) {\n memset(ll_header + len, 0, dev->hard_header_len - len);\n return true;\n }\n\nPacket send paths call dev_validate_header() on skbs whose headroom was\nallocated from an earlier hard_header_len read. If the device is\nreconfigured so that dev->hard_header_len increases before validation,\nthe memset writes past the reserved buffer, an out-of-bounds write.\n\nThis out-of-bounds write is masked in some SOCK_RAW paths today because\nthe same concurrent increase can first make skb_push() exceed the\nreserved headroom and trigger skb_under_panic(). Remove the zero-padding\nbranch before making those hard_header_len reads consistent, so the\nsnapshot fixes do not turn a loud panic into a silent overwrite.\n\nThis path is only reached for variable length L2 protocols, where\nlen < hard_header_len but len >= min_header_len. No remaining in-tree\nvariable length L2 protocol implements header_ops->validate, and the\nCAP_SYS_RAWIO bypass that zero-pads and accepts short headers has no\nreal value beyond allowing testing of intentionally malformed input.\n\nDrop the CAP_SYS_RAWIO branch. The remaining reads of\ndev->hard_header_len in dev_validate_header() are comparisons only and\nhave no memory safety impact." } ], "metrics": [ { "cvssV3_1": { "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" }, "scenarios": [ { "lang": "en", "value": "AV:L - Exploitation requires a local sendmsg() on a PF_PACKET SOCK_RAW socket; dev_validate_header() is only reached from af_packet transmit paths (packet_snd, packet_sendmsg_spkt, tpacket_fill_skb), not from remote packet receive.\nAC:L - The attacker can reliably win the TOCTOU race by concurrently sending PF_PACKET frames while changing netdev hard_header_len (e.g., PPP channel attach or bonding slave updates via rtnetlink), controlling both allocation and validation sides.\nPR:L - PF_PACKET creation requires CAP_NET_RAW and the memset bypass requires CAP_SYS_RAWIO; both are granted to user-namespace root (CAP_FULL_SET via unshare -Urn), so a basic unprivileged local user can obtain the needed privileges without init-namespace root.\nUI:N - No victim interaction is required; exploitation is fully attacker-driven through socket creation, concurrent device reconfiguration, and crafted sendmsg() calls.\nS:U - Impact is kernel heap memory corruption and local privilege escalation within the same kernel security domain, not a VM escape, IOMMU bypass, or other cross-authority boundary violation.\nC:H - The bug is an out-of-bounds write via memset() past skb link-layer headroom when hard_header_len grows between allocation and validation; such heap corruption can be groomed into arbitrary kernel memory read primitives.\nI:H - Writing past the reserved skb headroom corrupts adjacent kernel heap objects and is a standard exploitable primitive for arbitrary kernel writes, control-flow hijacking, and privilege escalation.\nA:H - The out-of-bounds memset can corrupt critical kernel structures and trigger oops/panic; the commit notes this can silently overwrite memory where other SOCK_RAW paths would have panicked via skb_under_panic." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/linux/netdevice.h" ], "versions": [ { "version": "b5518429e70cd783b8ca52335456172c1a0589f6", "lessThan": "53fd7f912c0877647d6a1e1877f5ea8535ee0b4a", "status": "affected", "versionType": "git" }, { "version": "2793a23aacbd754dbbb5cb75093deb7e4103bace", "lessThan": "fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6", "status": "affected", "versionType": "git" }, { "version": "2793a23aacbd754dbbb5cb75093deb7e4103bace", "lessThan": "8fc9816404166a90ed8d544dc52482fafffb6d9f", "status": "affected", "versionType": "git" }, { "version": "2793a23aacbd754dbbb5cb75093deb7e4103bace", "lessThan": "b0f92a5731dc82556a9ae005cc35f71ab136307b", "status": "affected", "versionType": "git" }, { "version": "2793a23aacbd754dbbb5cb75093deb7e4103bace", "lessThan": "99df6b7a713f96eda206680d100b76e15f9d9b69", "status": "affected", "versionType": "git" }, { "version": "2793a23aacbd754dbbb5cb75093deb7e4103bace", "lessThan": "74e035f07f53feca09e2352e77fccb09cad5e208", "status": "affected", "versionType": "git" }, { "version": "2793a23aacbd754dbbb5cb75093deb7e4103bace", "lessThan": "dbb30dc943a93e083f1e531bfdc6779e57de40d0", "status": "affected", "versionType": "git" }, { "version": "2793a23aacbd754dbbb5cb75093deb7e4103bace", "lessThan": "fc902f52a02298c7432b2334c0c82a2885a1a8b6", "status": "affected", "versionType": "git" }, { "version": "2793a23aacbd754dbbb5cb75093deb7e4103bace", "lessThan": "3b9a324e646d3657a8d9806dfbfe4f3e4066e882", "status": "affected", "versionType": "git" }, { "version": "f58a6c08ebdfa978178bbca78c2ba744a2665912", "status": "affected", "versionType": "git" }, { "version": "1df16498dfd0d5a129bdf2982d9a08df73e8923d", "status": "affected", "versionType": "git" }, { "version": "8b8d278aa4de9335682bbd4a3bb619af015c859e", "status": "affected", "versionType": "git" }, { "version": "6804052fa9d86e9a512c88b24a5debbfc1a490fc", "status": "affected", "versionType": "git" }, { "version": "3.2.80", "lessThan": "3.2.81", "status": "affected", "versionType": "semver" }, { "version": "3.16.36", "lessThan": "3.17", "status": "affected", "versionType": "semver" }, { "version": "4.1.28", "lessThan": "4.2", "status": "affected", "versionType": "semver" }, { "version": "4.4.8", "lessThan": "4.5", "status": "affected", "versionType": "semver" }, { "version": "4.5.2", "lessThan": "4.6", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/linux/netdevice.h" ], "versions": [ { "version": "4.6", "status": "affected" }, { "version": "0", "lessThan": "4.6", "status": "unaffected", "versionType": "semver" }, { "version": "3.2.81", "lessThanOrEqual": "3.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.265", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.152", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.104", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.45", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.9", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.2.80", "versionEndExcluding": "3.2.81" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6", "versionEndExcluding": "5.10.265" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6", "versionEndExcluding": "5.15.216" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6", "versionEndExcluding": "6.6.152" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6", "versionEndExcluding": "6.12.104" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6", "versionEndExcluding": "6.18.45" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6", "versionEndExcluding": "7.1.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6", "versionEndExcluding": "7.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.16.36" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1.28" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/53fd7f912c0877647d6a1e1877f5ea8535ee0b4a" }, { "url": "https://git.kernel.org/stable/c/fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6" }, { "url": "https://git.kernel.org/stable/c/8fc9816404166a90ed8d544dc52482fafffb6d9f" }, { "url": "https://git.kernel.org/stable/c/b0f92a5731dc82556a9ae005cc35f71ab136307b" }, { "url": "https://git.kernel.org/stable/c/99df6b7a713f96eda206680d100b76e15f9d9b69" }, { "url": "https://git.kernel.org/stable/c/74e035f07f53feca09e2352e77fccb09cad5e208" }, { "url": "https://git.kernel.org/stable/c/dbb30dc943a93e083f1e531bfdc6779e57de40d0" }, { "url": "https://git.kernel.org/stable/c/fc902f52a02298c7432b2334c0c82a2885a1a8b6" }, { "url": "https://git.kernel.org/stable/c/3b9a324e646d3657a8d9806dfbfe4f3e4066e882" } ], "title": "net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header", "x_generator": { "engine": "bippy-1.2.0" } } } }