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CVE-2026-80978

net: cap advertised IP tunnel headroom

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 1a37e412a0225fcba5587f24c0dfc7636efc8b69 · fixed in fb889a619723032140f5d983a3a34d25a5a2bed4; From 1a37e412a0225fcba5587f24c0dfc7636efc8b69 · fixed in b160422f8103574425e2834130e169d84c94fa1d; From 1a37e412a0225fcba5587f24c0dfc7636efc8b69 · fixed in d36e75f5669140b66515ad3a176ca6337bd80a5e; From 1a37e412a0225fcba5587f24c0dfc7636efc8b69 · fixed in 84783961cb8bdb36b4f41a02ce43aafc6d52b176; From 1a37e412a0225fcba5587f24c0dfc7636efc8b69 · fixed in bc4e05ae66c9797a0972ac44326e69c5305e0020; From 1a37e412a0225fcba5587f24c0dfc7636efc8b69 · fixed in af0ee8f04bea22cdb331fa3509e17f81b48938ad; From 1a37e412a0225fcba5587f24c0dfc7636efc8b69 · fixed in 9144f2c53a04465a6878172b523f640313c5559e; From 1a37e412a0225fcba5587f24c0dfc7636efc8b69 · fixed in 6b222adeb9340306e2ff97127c76117abb9b3df8

  • Linux Linux

    3.11

  • KernelLinux

    From 3.11.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4

References 8

git.kernel.org