CVE-2026-80978

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux1a37e412a0225fcba5587f24c0dfc7636efc8b69 < bc4e05ae66c9797a0972ac44326e69c5305e0020affected
LinuxLinux1a37e412a0225fcba5587f24c0dfc7636efc8b69 < af0ee8f04bea22cdb331fa3509e17f81b48938adaffected
LinuxLinux1a37e412a0225fcba5587f24c0dfc7636efc8b69 < 9144f2c53a04465a6878172b523f640313c5559eaffected
LinuxLinux1a37e412a0225fcba5587f24c0dfc7636efc8b69 < 6b222adeb9340306e2ff97127c76117abb9b3df8affected
LinuxLinux3.11affected
LinuxLinux0 < 3.11unaffected
LinuxLinux6.12.109 <= 6.12.*unaffected
LinuxLinux6.18.50 <= 6.18.*unaffected
LinuxLinux7.2.4 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References