net: tun: bound receive headroom
In 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.
CVE-2026-81000
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-81000
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "eaea34b23c46bf17b4a5638be69ab3561854f34b",
"lessThan": "ad715e713610d2d5473c3a6498c825ccecf26491",
"versionType": "git"
},
{
"status": "affected",
"version": "eaea34b23c46bf17b4a5638be69ab3561854f34b",
"lessThan": "708e87937de93f445225c134a2e20519f9b4ce60",
"versionType": "git"
},
{
"status": "affected",
"version": "eaea34b23c46bf17b4a5638be69ab3561854f34b",
"lessThan": "18ef24cdb2eba32e38f1d27f2d02b7b4212e8f76",
"versionType": "git"
},
{
"status": "affected",
"version": "eaea34b23c46bf17b4a5638be69ab3561854f34b",
"lessThan": "010eee265d6bd8769b6a523d2a0693d9b3f5df43",
"versionType": "git"
},
{
"status": "affected",
"version": "eaea34b23c46bf17b4a5638be69ab3561854f34b",
"lessThan": "379d85c7f25f3e05a428225e6b8a65613c6e9b9d",
"versionType": "git"
},
{
"status": "affected",
"version": "eaea34b23c46bf17b4a5638be69ab3561854f34b",
"lessThan": "e098d9cc8859614a7f7baebc96e32a5a16b18ed2",
"versionType": "git"
},
{
"status": "affected",
"version": "eaea34b23c46bf17b4a5638be69ab3561854f34b",
"lessThan": "0ada54ea63e48b9c1608e917ccb7dfadbe86db28",
"versionType": "git"
},
{
"status": "affected",
"version": "eaea34b23c46bf17b4a5638be69ab3561854f34b",
"lessThan": "447c9303942c439a117d9b76ce6d6e2116b38ee7",
"versionType": "git"
}
],
"programFiles": [
"drivers/net/tun.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.6"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.6",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/net/tun.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-81000
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #34954 · Revision 1
- Added to Heist Feed
- Publisher date