{"id":"CVE-2026-80731","summary":"net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header","details":"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-\u003ehard_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-\u003ehard_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-\u003ehard_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 \u003c hard_header_len but len \u003e= min_header_len. No remaining in-tree\nvariable length L2 protocol implements header_ops-\u003evalidate, 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-\u003ehard_header_len in dev_validate_header() are comparisons only and\nhave no memory safety impact.","modified":"2026-09-05T03:48:34.853242184Z","published":"2026-09-03T08:21:48.924Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80731.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/3b9a324e646d3657a8d9806dfbfe4f3e4066e882"},{"type":"WEB","url":"https://git.kernel.org/stable/c/53fd7f912c0877647d6a1e1877f5ea8535ee0b4a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/74e035f07f53feca09e2352e77fccb09cad5e208"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8fc9816404166a90ed8d544dc52482fafffb6d9f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/99df6b7a713f96eda206680d100b76e15f9d9b69"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b0f92a5731dc82556a9ae005cc35f71ab136307b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dbb30dc943a93e083f1e531bfdc6779e57de40d0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fc902f52a02298c7432b2334c0c82a2885a1a8b6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80731.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80731"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"b5518429e70cd783b8ca52335456172c1a0589f6"},{"fixed":"53fd7f912c0877647d6a1e1877f5ea8535ee0b4a"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"2793a23aacbd754dbbb5cb75093deb7e4103bace"},{"fixed":"fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6"},{"fixed":"8fc9816404166a90ed8d544dc52482fafffb6d9f"},{"fixed":"b0f92a5731dc82556a9ae005cc35f71ab136307b"},{"fixed":"99df6b7a713f96eda206680d100b76e15f9d9b69"},{"fixed":"74e035f07f53feca09e2352e77fccb09cad5e208"},{"fixed":"dbb30dc943a93e083f1e531bfdc6779e57de40d0"},{"fixed":"fc902f52a02298c7432b2334c0c82a2885a1a8b6"},{"fixed":"3b9a324e646d3657a8d9806dfbfe4f3e4066e882"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"f58a6c08ebdfa978178bbca78c2ba744a2665912"},{"last_affected":"1df16498dfd0d5a129bdf2982d9a08df73e8923d"},{"last_affected":"8b8d278aa4de9335682bbd4a3bb619af015c859e"},{"last_affected":"6804052fa9d86e9a512c88b24a5debbfc1a490fc"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3.2.80"},{"fixed":"3.2.81"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3.16.36"},{"fixed":"3.17"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"4.1.28"},{"fixed":"4.2"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"4.4.8"},{"fixed":"4.5"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"4.5.2"},{"fixed":"4.6"}]}],"versions":["v3.2.80","v4.1.27","v4.1.26","v3.16.35","v4.1.25","v4.5-rc4","v4.1.24","v4.1.23","v4.5","v4.5.1","v4.4.7","v4.1.22","v4.4.6","v4.1.21","v4.4","v4.5-rc1","v4.5-rc6","v4.1.20","v4.4.5","v4.5-rc2","v4.5-rc7","v4.5-rc5","v4.4.4","v4.5-rc3","v4.1.19","v4.4.3","v4.4.2","v4.1.18","v4.4.1","v4.1.17","v4.1.16","v4.1.15","v4.4-rc1","v4.4-rc2","v4.4-rc8","v4.4-rc3","v4.4-rc7","v4.4-rc5","v4.4-rc6","v4.4-rc4","v4.3","v4.1.14","v4.1.13","v4.3-rc1","v4.1.12","v4.3-rc6","v4.3-rc4","v4.3-rc2","v4.3-rc7","v4.3-rc5","v4.3-rc3","v4.1.11","v4.1.10","v4.2","v4.1.9","v4.1.8","v4.1.7","v4.1.6","v4.2-rc2","v4.2-rc1","v4.2-rc8","v4.2-rc4","v4.2-rc6","v4.2-rc7","v4.0-rc5","v4.1.5","v4.2-rc5","v4.1.4","v4.2-rc3","v4.1.3","v4.1.2","v4.1-rc2","v4.1","v4.1.1","v4.1-rc1","v4.1-rc8","v4.1-rc7","v4.1-rc6","v4.1-rc3","v4.1-rc4","v4.0","v4.1-rc5","v4.0-rc1","v4.0-rc2","v4.0-rc7","v4.0-rc3","v4.0-rc6","v4.0-rc4","v3.19","v3.19-rc7","v3.19-rc5","v3.19-rc1","v3.19-rc6","v3.19-rc4","v3.18-rc1","v3.19-rc3","v3.19-rc2","v3.18","v3.18-rc7","v3.18-rc6","v3.18-rc2","v3.18-rc3","v3.18-rc4","v3.18-rc5","v3.17","v3.16.7","v3.16.6","v3.17-rc1","v3.16.5","v3.17-rc7","v3.16.4","v3.17-rc2","v3.16.3","v3.17-rc4","v3.16","v3.17-rc5","v3.17-rc6","v3.16.2","v3.17-rc3","v3.16.1","v3.16-rc7","v3.16-rc1","v3.16-rc3","v3.16-rc5","v3.16-rc6","v3.16-rc2","v3.16-rc4","v3.13","v3.15","v3.15-rc5","v3.15-rc8","v3.15-rc1","v3.15-rc6","v3.15-rc3","v3.15-rc7","v3.15-rc2","v3.15-rc4","v3.14","v3.14-rc4","v3.14-rc8","v3.14-rc7","v3.14-rc6","v3.14-rc1","v3.14-rc2","v3.14-rc5","v3.14-rc3","v3.13-rc6","v3.13-rc8","v3.12","v3.13-rc7","v3.13-rc1","v3.13-rc4","v3.13-rc3","v3.13-rc5","v3.13-rc2","v3.12-rc7","v3.12-rc3","v3.12-rc6","v3.12-rc1","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