{"id":"CVE-2026-80731","state":"PUBLISHED","title":"net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header","description":"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.","publishedAt":"2026-09-03T08:21:48.924Z","updatedAt":"2026-10-16T19:26:36.020Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b5518429e70cd783b8ca52335456172c1a0589f6","status":"affected","lessThan":"53fd7f912c0877647d6a1e1877f5ea8535ee0b4a","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"8fc9816404166a90ed8d544dc52482fafffb6d9f","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"b0f92a5731dc82556a9ae005cc35f71ab136307b","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"99df6b7a713f96eda206680d100b76e15f9d9b69","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"74e035f07f53feca09e2352e77fccb09cad5e208","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"dbb30dc943a93e083f1e531bfdc6779e57de40d0","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"fc902f52a02298c7432b2334c0c82a2885a1a8b6","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"3b9a324e646d3657a8d9806dfbfe4f3e4066e882","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","status":"affected","lessThan":"3.2.81","versionType":"semver"},{"version":"3.16.36","status":"affected","lessThan":"3.17","versionType":"semver"},{"version":"4.1.28","status":"affected","lessThan":"4.2","versionType":"semver"},{"version":"4.4.8","status":"affected","lessThan":"4.5","versionType":"semver"},{"version":"4.5.2","status":"affected","lessThan":"4.6","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/netdevice.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.6","versionType":"semver"},{"version":"3.2.81","status":"unaffected","lessThanOrEqual":"3.2.*","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/netdevice.h"]}],"references":["https://git.kernel.org/stable/c/53fd7f912c0877647d6a1e1877f5ea8535ee0b4a","https://git.kernel.org/stable/c/fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6","https://git.kernel.org/stable/c/8fc9816404166a90ed8d544dc52482fafffb6d9f","https://git.kernel.org/stable/c/b0f92a5731dc82556a9ae005cc35f71ab136307b","https://git.kernel.org/stable/c/99df6b7a713f96eda206680d100b76e15f9d9b69","https://git.kernel.org/stable/c/74e035f07f53feca09e2352e77fccb09cad5e208","https://git.kernel.org/stable/c/dbb30dc943a93e083f1e531bfdc6779e57de40d0","https://git.kernel.org/stable/c/fc902f52a02298c7432b2334c0c82a2885a1a8b6","https://git.kernel.org/stable/c/3b9a324e646d3657a8d9806dfbfe4f3e4066e882"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80731.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80731","state":"PUBLISHED","datePublished":"2026-09-03T08:21:48.924Z","dateUpdated":"2026-10-16T19:26:36.020Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.789Z"},"containers":{"cna":{"title":"net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b5518429e70cd783b8ca52335456172c1a0589f6","status":"affected","lessThan":"53fd7f912c0877647d6a1e1877f5ea8535ee0b4a","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"8fc9816404166a90ed8d544dc52482fafffb6d9f","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"b0f92a5731dc82556a9ae005cc35f71ab136307b","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"99df6b7a713f96eda206680d100b76e15f9d9b69","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"74e035f07f53feca09e2352e77fccb09cad5e208","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"dbb30dc943a93e083f1e531bfdc6779e57de40d0","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"fc902f52a02298c7432b2334c0c82a2885a1a8b6","versionType":"git"},{"version":"2793a23aacbd754dbbb5cb75093deb7e4103bace","status":"affected","lessThan":"3b9a324e646d3657a8d9806dfbfe4f3e4066e882","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","status":"affected","lessThan":"3.2.81","versionType":"semver"},{"version":"3.16.36","status":"affected","lessThan":"3.17","versionType":"semver"},{"version":"4.1.28","status":"affected","lessThan":"4.2","versionType":"semver"},{"version":"4.4.8","status":"affected","lessThan":"4.5","versionType":"semver"},{"version":"4.5.2","status":"affected","lessThan":"4.6","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/netdevice.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.6","versionType":"semver"},{"version":"3.2.81","status":"unaffected","lessThanOrEqual":"3.2.*","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/netdevice.h"]}],"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-09-04T04:58:17.510Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-80731","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T19:21:14.341917Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:26:36.020Z"}}]}}}