CVE-2025-40173
net/ip6_tunnel: Prevent perpetual tunnel growth
Vexday Risk Score
3Low
SSVC decision (CISA)
Track
No exploitation signal → monitor
CVSS —EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —
Lifecycle
12 Nov 2025Published on NVD
Recommendation: Monitor — no exploitation signal at the moment.
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 · LinuxReferences
https://git.kernel.org/stable/c/10fe967efe73c610e526ff7460581610633dee9chttps://git.kernel.org/stable/c/11f6066af3bfb8149aa16c42c0b0c5ea5b199a94https://git.kernel.org/stable/c/21f4d45eba0b2dcae5dbc9e5e0ad08735c993f16https://git.kernel.org/stable/c/402b6985e872b4cf394bbbf33b503947a326a6cbhttps://git.kernel.org/stable/c/48294a67863c9cfa367abb66bbf0ef6548ae124fhttps://git.kernel.org/stable/c/566f8d5c8a443f2dd69c5460fdec43ed1c870c65https://git.kernel.org/stable/c/b6eb25d870f1a8ae571fd3da2244b71df547824bhttps://git.kernel.org/stable/c/eeb4345488672584db4f8c20a1ae13a212ce31c4