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CVE-2025-40173

net/ip6_tunnel: Prevent perpetual tunnel growth

HIGH
7.8
CVSS Score
Published: November 12, 2025 at 10:53 AM UTC
Updated: October 19, 2026 at 09:10 PM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
HIGH7.8
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel· Linux
90%
4.78eb30be0352d09165e94a41fef1c7b994dca0714
Vendor states this is fixed in 10fe967efe73c610e526ff7460581610633dee9c (fixed)
Vendor states this is fixed in 11f6066af3bfb8149aa16c42c0b0c5ea5b199a94 (fixed)
Vendor states this is fixed in 21f4d45eba0b2dcae5dbc9e5e0ad08735c993f16 (fixed)
Vendor states this is fixed in 402b6985e872b4cf394bbbf33b503947a326a6cb (fixed)
Vendor states this is fixed in 48294a67863c9cfa367abb66bbf0ef6548ae124f (fixed)
Vendor states this is fixed in 566f8d5c8a443f2dd69c5460fdec43ed1c870c65 (fixed)
Vendor states this is fixed in b6eb25d870f1a8ae571fd3da2244b71df547824b (fixed)
Vendor states this is fixed in eeb4345488672584db4f8c20a1ae13a212ce31c4 (fixed)
Vendor states this is fixed in 4.7 (unaffected)
Vendor states this is fixed in 5.10.246 (unaffected)
Vendor states this is fixed in 5.15.196 (unaffected)
Vendor states this is fixed in 5.4.301 (unaffected)
Vendor states this is fixed in 6.1.158 (unaffected)
Vendor states this is fixed in 6.12.55 (unaffected)
Vendor states this is fixed in 6.17.5 (unaffected)
Vendor states this is fixed in 6.18 (unaffected)
Vendor states this is fixed in 6.6.114 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (8)

Source: cverecord
https://git.kernel.org/stable/c/566f8d5c8a443f2dd69c5460fdec43ed1c870c65
Source: cverecord
https://git.kernel.org/stable/c/11f6066af3bfb8149aa16c42c0b0c5ea5b199a94
Source: cverecord
https://git.kernel.org/stable/c/402b6985e872b4cf394bbbf33b503947a326a6cb
Source: cverecord
https://git.kernel.org/stable/c/10fe967efe73c610e526ff7460581610633dee9c
Source: cverecord
https://git.kernel.org/stable/c/48294a67863c9cfa367abb66bbf0ef6548ae124f
Source: cverecord
https://git.kernel.org/stable/c/eeb4345488672584db4f8c20a1ae13a212ce31c4
Source: cverecord
https://git.kernel.org/stable/c/b6eb25d870f1a8ae571fd3da2244b71df547824b
Source: cverecord
https://git.kernel.org/stable/c/21f4d45eba0b2dcae5dbc9e5e0ad08735c993f16

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGHLinux
Vector?

Quick Info

StatusDEFERRED

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