{"api_version":"1","generated_at":"2026-09-13T06:11:19+00:00","cve":"CVE-2026-81000","urls":{"html":"https://cve.report/CVE-2026-81000","api":"https://cve.report/api/cve/CVE-2026-81000.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-81000","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-81000"},"summary":{"title":"net: tun: bound receive headroom","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tun: bound receive headroom\n\ntun_get_user() uses tun->align both as skb headroom and when choosing how\nmuch packet data to keep linear. OVS can propagate an oversized headroom\nrequest from another port to TUN or TAP.\n\nWhen align is larger than the usable space in a one-page skb head,\nSKB_MAX_HEAD(align) underflows and the result becomes negative when stored\nin good_linear. That value later wraps when assigned to the size_t linear\nvariable, and tun_alloc_skb() can place skb->data outside the allocated\nhead.\n\nBound the headroom stored by TUN to the one-page skb-head budget and the\nlargest non-sentinel 16-bit skb header offset. Leave one linear byte for\nraw TUN and a complete Ethernet header for TAP, including NET_IP_ALIGN.\n\nAlso pull the raw-TUN protocol byte and the TAP Ethernet header before\naccessing them, so these checks remain safe for nonlinear skbs supplied by\nother allocation paths.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:07","updated_at":"2026-09-11 20:19:07"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/379d85c7f25f3e05a428225e6b8a65613c6e9b9d","name":"https://git.kernel.org/stable/c/379d85c7f25f3e05a428225e6b8a65613c6e9b9d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/447c9303942c439a117d9b76ce6d6e2116b38ee7","name":"https://git.kernel.org/stable/c/447c9303942c439a117d9b76ce6d6e2116b38ee7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e098d9cc8859614a7f7baebc96e32a5a16b18ed2","name":"https://git.kernel.org/stable/c/e098d9cc8859614a7f7baebc96e32a5a16b18ed2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0ada54ea63e48b9c1608e917ccb7dfadbe86db28","name":"https://git.kernel.org/stable/c/0ada54ea63e48b9c1608e917ccb7dfadbe86db28","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-81000","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-81000","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected eaea34b23c46bf17b4a5638be69ab3561854f34b 379d85c7f25f3e05a428225e6b8a65613c6e9b9d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected eaea34b23c46bf17b4a5638be69ab3561854f34b e098d9cc8859614a7f7baebc96e32a5a16b18ed2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected eaea34b23c46bf17b4a5638be69ab3561854f34b 0ada54ea63e48b9c1608e917ccb7dfadbe86db28 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected eaea34b23c46bf17b4a5638be69ab3561854f34b 447c9303942c439a117d9b76ce6d6e2116b38ee7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.6","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.6 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"81000","cve":"CVE-2026-81000","epss":"0.002000000","percentile":"0.099650000","score_date":"2026-09-12","updated_at":"2026-09-13 00:08:17"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/net/tun.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"379d85c7f25f3e05a428225e6b8a65613c6e9b9d","status":"affected","version":"eaea34b23c46bf17b4a5638be69ab3561854f34b","versionType":"git"},{"lessThan":"e098d9cc8859614a7f7baebc96e32a5a16b18ed2","status":"affected","version":"eaea34b23c46bf17b4a5638be69ab3561854f34b","versionType":"git"},{"lessThan":"0ada54ea63e48b9c1608e917ccb7dfadbe86db28","status":"affected","version":"eaea34b23c46bf17b4a5638be69ab3561854f34b","versionType":"git"},{"lessThan":"447c9303942c439a117d9b76ce6d6e2116b38ee7","status":"affected","version":"eaea34b23c46bf17b4a5638be69ab3561854f34b","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/net/tun.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.6"},{"lessThan":"4.6","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","versionStartIncluding":"4.6","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"4.6","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"4.6","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"4.6","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tun: bound receive headroom\n\ntun_get_user() uses tun->align both as skb headroom and when choosing how\nmuch packet data to keep linear. OVS can propagate an oversized headroom\nrequest from another port to TUN or TAP.\n\nWhen align is larger than the usable space in a one-page skb head,\nSKB_MAX_HEAD(align) underflows and the result becomes negative when stored\nin good_linear. That value later wraps when assigned to the size_t linear\nvariable, and tun_alloc_skb() can place skb->data outside the allocated\nhead.\n\nBound the headroom stored by TUN to the one-page skb-head budget and the\nlargest non-sentinel 16-bit skb header offset. Leave one linear byte for\nraw TUN and a complete Ethernet header for TAP, including NET_IP_ALIGN.\n\nAlso pull the raw-TUN protocol byte and the TAP Ethernet header before\naccessing them, so these checks remain safe for nonlinear skbs supplied by\nother allocation paths."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:42:54.181Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/379d85c7f25f3e05a428225e6b8a65613c6e9b9d"},{"url":"https://git.kernel.org/stable/c/e098d9cc8859614a7f7baebc96e32a5a16b18ed2"},{"url":"https://git.kernel.org/stable/c/0ada54ea63e48b9c1608e917ccb7dfadbe86db28"},{"url":"https://git.kernel.org/stable/c/447c9303942c439a117d9b76ce6d6e2116b38ee7"}],"title":"net: tun: bound receive headroom","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-81000","datePublished":"2026-09-11T19:42:54.181Z","dateReserved":"2026-08-26T14:34:25.812Z","dateUpdated":"2026-09-11T19:42:54.181Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:07","lastModifiedDate":"2026-09-11 20:19:07","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"81000","Ordinal":"1","Title":"net: tun: bound receive headroom","CVE":"CVE-2026-81000","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"81000","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tun: bound receive headroom\n\ntun_get_user() uses tun->align both as skb headroom and when choosing how\nmuch packet data to keep linear. OVS can propagate an oversized headroom\nrequest from another port to TUN or TAP.\n\nWhen align is larger than the usable space in a one-page skb head,\nSKB_MAX_HEAD(align) underflows and the result becomes negative when stored\nin good_linear. That value later wraps when assigned to the size_t linear\nvariable, and tun_alloc_skb() can place skb->data outside the allocated\nhead.\n\nBound the headroom stored by TUN to the one-page skb-head budget and the\nlargest non-sentinel 16-bit skb header offset. Leave one linear byte for\nraw TUN and a complete Ethernet header for TAP, including NET_IP_ALIGN.\n\nAlso pull the raw-TUN protocol byte and the TAP Ethernet header before\naccessing them, so these checks remain safe for nonlinear skbs supplied by\nother allocation paths.","Type":"Description","Title":"net: tun: bound receive headroom"}]}}}