{"id":"CVE-2026-80731","title":"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 …","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","cwe":["CWE-787"],"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 8","enterprise_linux 9","openshift_container_platform 4"],"published":"2026-09-03","updated":"2026-10-16","sourceUpdated":"2026-10-16T20:18:09.420","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-80731","references":[{"url":"https://git.kernel.org/stable/c/3b9a324e646d3657a8d9806dfbfe4f3e4066e882","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/53fd7f912c0877647d6a1e1877f5ea8535ee0b4a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/74e035f07f53feca09e2352e77fccb09cad5e208","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8fc9816404166a90ed8d544dc52482fafffb6d9f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/99df6b7a713f96eda206680d100b76e15f9d9b69","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b0f92a5731dc82556a9ae005cc35f71ab136307b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/dbb30dc943a93e083f1e531bfdc6779e57de40d0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fc902f52a02298c7432b2334c0c82a2885a1a8b6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80731.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-80731"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2527871"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80731"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80731"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80731.mbox"},{"url":"https://kernelcve.org/list/?q=CVE-2026-80731"}],"tags":["nvd","csaf","vex","red-hat","cve.org","score-dispute"],"epss":0.00142,"epssPercentile":0.03439,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T19:21:14.341917Z"},"scores":{"nvd":7.8,"vendor":4.7,"cna":7.8},"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## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80731.json)","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":230439,"id":"CVE-2026-80731","ts":1793134644251,"field":"cvss","old":"4.7","new":"7.8"},{"seq":230438,"id":"CVE-2026-80731","ts":1793134644251,"field":"severity","old":"medium","new":"high"},{"seq":229442,"id":"CVE-2026-80731","ts":1793019777960,"field":"cvss","old":"7.8","new":"4.7"},{"seq":229441,"id":"CVE-2026-80731","ts":1793019777960,"field":"severity","old":"high","new":"medium"}]}