CVE-2026-80978
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net: cap advertised IP tunnel headroom IP tunnel devices derive their advertised needed_headroom from lower output devices. A stack of user-created devices can make the derived value larger than the 16-bit skb header offsets can represent. Once IP output reserves it, skb head expansion can wrap those offsets. The runtime transmit path already caps a growing needed_headroom at 512. Apply the same cap when tunnel configuration publishes needed_headroom derived from a lower output device. Capping the advertised value is safe: IP tunnel transmit still expands the skb when a packet needs more headroom. A nonsensical stacked configuration can therefore incur an extra reallocation, but it cannot publish an unbounded reservation to upper layers.
Severity
HIGH
CVSS score
7.8
(v3.1)
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-09-11 20:19:04.143000
Last modified
2026-10-19 09:17:30.010000
View original CVE JSON
{
"id": "CVE-2026-80978",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-11T20:19:04.143",
"lastModified": "2026-10-19T09:17:30.010",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: cap advertised IP tunnel headroom\n\nIP tunnel devices derive their advertised needed_headroom from lower\noutput devices. A stack of user-created devices can make the derived\nvalue larger than the 16-bit skb header offsets can represent. Once IP\noutput reserves it, skb head expansion can wrap those offsets.\n\nThe runtime transmit path already caps a growing needed_headroom at 512.\nApply the same cap when tunnel configuration publishes needed_headroom\nderived from a lower output device.\n\nCapping the advertised value is safe: IP tunnel transmit still expands\nthe skb when a packet needs more headroom. A nonsensical stacked\nconfiguration can therefore incur an extra reallocation, but it cannot\npublish an unbounded reservation to upper layers."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"include/net/ip_tunnels.h",
"net/ipv4/ip_tunnel.c",
"net/ipv6/ip6_gre.c",
"net/ipv6/ip6_tunnel.c",
"net/ipv6/sit.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
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"lessThan": "fb889a619723032140f5d983a3a34d25a5a2bed4",
"versionType": "git",
"status": "affected"
},
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},
{
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"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"include/net/ip_tunnels.h",
"net/ipv4/ip_tunnel.c",
"net/ipv6/ip6_gre.c",
"net/ipv6/ip6_tunnel.c",
"net/ipv6/sit.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "3.11",
"status": "affected"
},
{
"version": "0",
"lessThan": "3.11",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.270",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.221",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.188",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.157",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.109",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.50",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.4",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
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{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"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",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-10-16T19:21:45.426777Z",
"id": "CVE-2026-80978",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"references": [
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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}