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Review reviewHigh

CVE-2025-40173

Linux

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.

CVSS
7.8
EPSS
0.14%
3.88% percentile
CISA KEV
Not listed
Published
2025.11.12
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.14%
Technical severityCVSS 7.8

Vulnerability overview

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 product and versions

Product
Linux
Affected versions
>= 8eb30be0352d09165e94a41fef1c7b994dca0714 < 566f8d5c8a443f2dd69c5460fdec43ed1c870c65, >= 8eb30be0352d09165e94a41fef1c7b994dca0714 < 11f6066af3bfb8149aa16c42c0b0c5ea5b199a94, >= 8eb30be0352d09165e94a41fef1c7b994dca0714 < 402b6985e872b4cf394bbbf33b503947a326a6cb, >= 8eb30be0352d09165e94a41fef1c7b994dca0714 < 10fe967efe73c610e526ff7460581610633dee9c, >= 8eb30be0352d09165e94a41fef1c7b994dca0714 < 48294a67863c9cfa367abb66bbf0ef6548ae124f, >= 8eb30be0352d09165e94a41fef1c7b994dca0714 < eeb4345488672584db4f8c20a1ae13a212ce31c4, >= 8eb30be0352d09165e94a41fef1c7b994dca0714 < b6eb25d870f1a8ae571fd3da2244b71df547824b, >= 8eb30be0352d09165e94a41fef1c7b994dca0714 < 21f4d45eba0b2dcae5dbc9e5e0ad08735c993f16, >= 4.7
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
Not available
CVE-2025-40173 — Linux | SECUFOCUS NOW