CVE-2025-40173

net/ip6_tunnel: Prevent perpetual tunnel growth

State: Published
Severity: 7.8 High
Published: Nov 12, 2025
Updated: Oct 15, 2026
Reserved: Apr 16, 2025

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	8eb30be0352d09165e94a41fef1c7b994dca0714 to before 566f8d5c8a443f2dd69c5460fdec43ed1c870c65Affected 8eb30be0352d09165e94a41fef1c7b994dca0714 to before 11f6066af3bfb8149aa16c42c0b0c5ea5b199a94Affected 8eb30be0352d09165e94a41fef1c7b994dca0714 to before 402b6985e872b4cf394bbbf33b503947a326a6cbAffected 8eb30be0352d09165e94a41fef1c7b994dca0714 to before 10fe967efe73c610e526ff7460581610633dee9cAffected 8eb30be0352d09165e94a41fef1c7b994dca0714 to before 48294a67863c9cfa367abb66bbf0ef6548ae124fAffected 8eb30be0352d09165e94a41fef1c7b994dca0714 to before eeb4345488672584db4f8c20a1ae13a212ce31c4Affected 8eb30be0352d09165e94a41fef1c7b994dca0714 to before b6eb25d870f1a8ae571fd3da2244b71df547824bAffected 8eb30be0352d09165e94a41fef1c7b994dca0714 to before 21f4d45eba0b2dcae5dbc9e5e0ad08735c993f16Affected
LinuxLinux	4.7Affected before 4.7Not affected 5.4.301 through 5.4.Not affected 5.10.246 through 5.10.Not affected 5.15.196 through 5.15.Not affected 6.1.158 through 6.1.Not affected 6.6.114 through 6.6.Not affected 6.12.55 through 6.12.Not affected 6.17.5 through 6.17.*Not affected 6.18 and laterNot affected

Product

Versions

LinuxLinux

8eb30be0352d09165e94a41fef1c7b994dca0714 to before 566f8d5c8a443f2dd69c5460fdec43ed1c870c65Affected
8eb30be0352d09165e94a41fef1c7b994dca0714 to before 11f6066af3bfb8149aa16c42c0b0c5ea5b199a94Affected
8eb30be0352d09165e94a41fef1c7b994dca0714 to before 402b6985e872b4cf394bbbf33b503947a326a6cbAffected
8eb30be0352d09165e94a41fef1c7b994dca0714 to before 10fe967efe73c610e526ff7460581610633dee9cAffected
8eb30be0352d09165e94a41fef1c7b994dca0714 to before 48294a67863c9cfa367abb66bbf0ef6548ae124fAffected
8eb30be0352d09165e94a41fef1c7b994dca0714 to before eeb4345488672584db4f8c20a1ae13a212ce31c4Affected
8eb30be0352d09165e94a41fef1c7b994dca0714 to before b6eb25d870f1a8ae571fd3da2244b71df547824bAffected
8eb30be0352d09165e94a41fef1c7b994dca0714 to before 21f4d45eba0b2dcae5dbc9e5e0ad08735c993f16Affected

LinuxLinux

4.7Affected
before 4.7Not affected
5.4.301 through 5.4.*Not affected
5.10.246 through 5.10.*Not affected
5.15.196 through 5.15.*Not affected
6.1.158 through 6.1.*Not affected
6.6.114 through 6.6.*Not affected
6.12.55 through 6.12.*Not affected
6.17.5 through 6.17.*Not affected
6.18 and laterNot affected

References

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