net: tun: bound receive headroom

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-81000
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:07 UTC
Updated2026-09-11 20:19:07 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: tun: bound receive headroom tun_get_user() uses tun->align both as skb headroom and when choosing how much packet data to keep linear. OVS can propagate an oversized headroom request from another port to TUN or TAP. When align is larger than the usable space in a one-page skb head, SKB_MAX_HEAD(align) underflows and the result becomes negative when stored in good_linear. That value later wraps when assigned to the size_t linear variable, and tun_alloc_skb() can place skb->data outside the allocated head. Bound the headroom stored by TUN to the one-page skb-head budget and the largest non-sentinel 16-bit skb header offset. Leave one linear byte for raw TUN and a complete Ethernet header for TAP, including NET_IP_ALIGN. Also pull the raw-TUN protocol byte and the TAP Ethernet header before accessing them, so these checks remain safe for nonlinear skbs supplied by other allocation paths.

Risk And Classification

EPSS: 0.002000000 probability, percentile 0.099650000 (date 2026-09-12)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected eaea34b23c46bf17b4a5638be69ab3561854f34b 379d85c7f25f3e05a428225e6b8a65613c6e9b9d git Not specified
CNA Linux Linux affected eaea34b23c46bf17b4a5638be69ab3561854f34b e098d9cc8859614a7f7baebc96e32a5a16b18ed2 git Not specified
CNA Linux Linux affected eaea34b23c46bf17b4a5638be69ab3561854f34b 0ada54ea63e48b9c1608e917ccb7dfadbe86db28 git Not specified
CNA Linux Linux affected eaea34b23c46bf17b4a5638be69ab3561854f34b 447c9303942c439a117d9b76ce6d6e2116b38ee7 git Not specified
CNA Linux Linux affected 4.6 Not specified
CNA Linux Linux unaffected 4.6 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/379d85c7f25f3e05a428225e6b8a65613c6e9b9d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/447c9303942c439a117d9b76ce6d6e2116b38ee7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e098d9cc8859614a7f7baebc96e32a5a16b18ed2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0ada54ea63e48b9c1608e917ccb7dfadbe86db28 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report