Linux Kernel up to 6.18-rc1 ip6_tunnel privilege escalation

CVSS Meta Temp Score
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CTI Interest Score
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5.3$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.18-rc1. This affects the function ip6_tunnel. Such manipulation leads to an unknown weakness. This vulnerability is referenced as CVE-2025-40173. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18-rc1. It has been rated as critical. The impact remains unknown. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2025-40173 since 04/16/2025. The exploitation is known to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 02/08/2026).

The vulnerability scanner Nessus provides a plugin with the ID 276782 (Debian dla-4379 : linux-config-6.1 - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.4.301, 5.10.246, 5.15.196, 6.1.158, 6.6.114, 6.12.55, 6.17.5 or 6.18-rc2 eliminates this vulnerability. Applying the patch 566f8d5c8a443f2dd69c5460fdec43ed1c870c65/11f6066af3bfb8149aa16c42c0b0c5ea5b199a94/402b6985e872b4cf394bbbf33b503947a326a6cb/10fe967efe73c610e526ff7460581610633dee9c/48294a67863c9cfa367abb66bbf0ef6548ae124f/eeb4345488672584db4f8c20a1ae13a212ce31c4/b6eb25d870f1a8ae571fd3da2244b71df547824b/21f4d45eba0b2dcae5dbc9e5e0ad08735c993f16 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (276782) and CERT Bund (WID-SEC-2025-2579). Once again VulDB remains the best source for vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Privilege escalation
CWE: Unknown
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 276782
Nessus Name: Debian dla-4379 : linux-config-6.1 - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.4.301/5.10.246/5.15.196/6.1.158/6.6.114/6.12.55/6.17.5/6.18-rc2
Patch: 566f8d5c8a443f2dd69c5460fdec43ed1c870c65/11f6066af3bfb8149aa16c42c0b0c5ea5b199a94/402b6985e872b4cf394bbbf33b503947a326a6cb/10fe967efe73c610e526ff7460581610633dee9c/48294a67863c9cfa367abb66bbf0ef6548ae124f/eeb4345488672584db4f8c20a1ae13a212ce31c4/b6eb25d870f1a8ae571fd3da2244b71df547824b/21f4d45eba0b2dcae5dbc9e5e0ad08735c993f16

Timelineinfo

04/16/2025 CVE reserved
11/12/2025 +210 days Advisory disclosed
11/12/2025 +0 days VulDB entry created
02/08/2026 +88 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40173 (🔒)
GCVE (CVE): GCVE-0-2025-40173
GCVE (VulDB): GCVE-100-332180
CERT Bund: WID-SEC-2025-2579 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 11/12/2025 13:38
Updated: 02/08/2026 13:47
Changes: 11/12/2025 13:38 (57), 11/28/2025 21:48 (2), 12/21/2025 04:02 (7), 12/30/2025 23:05 (1), 02/08/2026 13:47 (1)
Complete: 🔍
Cache ID: 216::103

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