CVE-2025-40173: Linux

High severity, CVSS 7.8. EPSS: 0.1% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: net/ip6_tunnel: Prevent perpetual tunnel growth Similarly to ipv4 tunnel, ipv6 version updates dev->needed_headroom, too. While ipv4 tunnel headroom adjustment growth was limited in commit 5ae1e9922bbd ("net: ip_tunnel: prevent perpetual headroom growth"), ipv6 tunnel yet increases the headroom without any ceiling. Reflect ipv4 tunnel headroom adjustment limit on ipv6 version. Credits to Francesco Ruggeri, who was originally debugging this issue and wrote local Arista-specific patch and a reproducer.

Affected products

• Linux Linux: from 4.7, before 5.4.301 (fixed in 5.4.301); from 5.5, before 5.10.246 (fixed in 5.10.246); from 5.11, before 5.15.196 (fixed in 5.15.196); from 5.16, before 6.1.158 (fixed in 6.1.158); from 6.2, before 6.6.114 (fixed in 6.6.114); from 6.7, before 6.12.55 (fixed in 6.12.55); …

Published 2025-11-12. Last modified 2026-07-30.