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net: cap advertised IP tunnel headroom

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-80978

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-2026-80978

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": "1a37e412a0225fcba5587f24c0dfc7636efc8b69",
        "lessThan": "fb889a619723032140f5d983a3a34d25a5a2bed4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1a37e412a0225fcba5587f24c0dfc7636efc8b69",
        "lessThan": "b160422f8103574425e2834130e169d84c94fa1d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1a37e412a0225fcba5587f24c0dfc7636efc8b69",
        "lessThan": "d36e75f5669140b66515ad3a176ca6337bd80a5e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1a37e412a0225fcba5587f24c0dfc7636efc8b69",
        "lessThan": "84783961cb8bdb36b4f41a02ce43aafc6d52b176",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1a37e412a0225fcba5587f24c0dfc7636efc8b69",
        "lessThan": "bc4e05ae66c9797a0972ac44326e69c5305e0020",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1a37e412a0225fcba5587f24c0dfc7636efc8b69",
        "lessThan": "af0ee8f04bea22cdb331fa3509e17f81b48938ad",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1a37e412a0225fcba5587f24c0dfc7636efc8b69",
        "lessThan": "9144f2c53a04465a6878172b523f640313c5559e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1a37e412a0225fcba5587f24c0dfc7636efc8b69",
        "lessThan": "6b222adeb9340306e2ff97127c76117abb9b3df8",
        "versionType": "git"
      }
    ],
    "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"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.11"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.11",
        "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": [
      "include/net/ip_tunnels.h",
      "net/ipv4/ip_tunnel.c",
      "net/ipv6/ip6_gre.c",
      "net/ipv6/ip6_tunnel.c",
      "net/ipv6/sit.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-80978

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#34936 · Revision 1
Added to Heist Feed
Publisher date
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