{"id":"CVE-2026-80731","title":"net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header","summary":"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 …","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 >= b5518429e70cd783b8ca52335456172c1a0589f6 < 53fd7f912c0877647d6a1e1877f5ea8535ee0b4a","Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6","Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < 8fc9816404166a90ed8d544dc52482fafffb6d9f","Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < b0f92a5731dc82556a9ae005cc35f71ab136307b","Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < 99df6b7a713f96eda206680d100b76e15f9d9b69","Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < 74e035f07f53feca09e2352e77fccb09cad5e208","Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < dbb30dc943a93e083f1e531bfdc6779e57de40d0","Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < fc902f52a02298c7432b2334c0c82a2885a1a8b6","Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < 3b9a324e646d3657a8d9806dfbfe4f3e4066e882","Linux f58a6c08ebdfa978178bbca78c2ba744a2665912","Linux 1df16498dfd0d5a129bdf2982d9a08df73e8923d","Linux 8b8d278aa4de9335682bbd4a3bb619af015c859e","Linux 6804052fa9d86e9a512c88b24a5debbfc1a490fc","Linux >= 3.2.80 < 3.2.81","Linux >= 3.16.36 < 3.17","Linux >= 4.1.28 < 4.2","Linux >= 4.4.8 < 4.5","Linux >= 4.5.2 < 4.6","Linux 4.6"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T19:21:14.341917Z"},"published":"2026-09-03","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:26:36.020Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80731","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"}],"tags":["cve.org"],"epss":0.00142,"epssPercentile":0.03103,"ingestedAt":"2026-10-16T19:46:24.301Z","slug":"CVE-2026-80731","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= b5518429e70cd783b8ca52335456172c1a0589f6 < 53fd7f912c0877647d6a1e1877f5ea8535ee0b4a`\n- `Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6`\n- `Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < 8fc9816404166a90ed8d544dc52482fafffb6d9f`\n- `Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < b0f92a5731dc82556a9ae005cc35f71ab136307b`\n- `Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < 99df6b7a713f96eda206680d100b76e15f9d9b69`\n- `Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < 74e035f07f53feca09e2352e77fccb09cad5e208`\n- `Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < dbb30dc943a93e083f1e531bfdc6779e57de40d0`\n- `Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < fc902f52a02298c7432b2334c0c82a2885a1a8b6`\n- `Linux >= 2793a23aacbd754dbbb5cb75093deb7e4103bace < 3b9a324e646d3657a8d9806dfbfe4f3e4066e882`\n- `Linux f58a6c08ebdfa978178bbca78c2ba744a2665912`\n- `Linux 1df16498dfd0d5a129bdf2982d9a08df73e8923d`\n- `Linux 8b8d278aa4de9335682bbd4a3bb619af015c859e`\n- `Linux 6804052fa9d86e9a512c88b24a5debbfc1a490fc`\n- `Linux >= 3.2.80 < 3.2.81`\n- `Linux >= 3.16.36 < 3.17`\n- `Linux >= 4.1.28 < 4.2`\n- `Linux >= 4.4.8 < 4.5`\n- `Linux >= 4.5.2 < 4.6`\n- `Linux 4.6`\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":[]}