VDB-292557 · CVE-2025-21646 · EUVD-2025-2595

Linux Kernel up to 6.1.124/6.6.71/6.12.9/6.13-rc6 afs /proc/net/afs/ privilege escalation

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5.4	$0-$5k	0.00

Summaryinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 6.1.124/6.6.71/6.12.9/6.13-rc6. Affected by this issue is some unknown functionality of the file /proc/net/afs/ of the component afs. Performing a manipulation results in an unknown weakness. This vulnerability is reported as CVE-2025-21646. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Linux Kernel up to 6.1.124/6.6.71/6.12.9/6.13-rc6. This affects some unknown processing of the file /proc/net/afs/ of the component afs. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: afs: Fix the maximum cell name length The kafs filesystem limits the maximum length of a cell to 256 bytes, but a problem occurs if someone actually does that: kafs tries to create a directory under /proc/net/afs/ with the name of the cell, but that fails with a warning: WARNING: CPU: 0 PID: 9 at fs/proc/generic.c:405 because procfs limits the maximum filename length to 255. However, the DNS limits the maximum lookup length and, by extension, the maximum cell name, to 255 less two (length count and trailing NUL). Fix this by limiting the maximum acceptable cellname length to 253. This also allows us to be sure we can create the "/afs/./" mountpoint too. Further, split the YFS VL record cell name maximum to be the 256 allowed by the protocol and ignore the record retrieved by YFSVL.GetCellName if it exceeds 253.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2025-21646 since 12/29/2024. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 215144 (Debian dsa-5860 : affs-modules-6.1.0-21-4kc-malta-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.125, 6.6.72, 6.12.10 or 6.13-rc7 eliminates this vulnerability. Applying the patch aabe47cf5ac5e1db2ae0635f189d836f67024904/7673030efe0f8ca1056d3849d61784c6caa052af/7922b1f058fe24a93730511dd0ae2e1630920096/8fd56ad6e7c90ac2bddb0741c6b248c8c5d56ac8 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 (215144), EUVD (EUVD-2025-2595) and CERT Bund (WID-SEC-2025-0119). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

Debian Linux
Amazon Linux 2
Red Hat Enterprise Linux
Ubuntu Linux
SUSE Linux
Oracle Linux
Dell NetWorker
Dell Avamar
Dell PowerProtect Data Domain
Open Source Linux Kernel

Productinfo

Type

Operating System

Vendor

Linux

Name

Kernel

Version

License

open-source

Website

Vendor: https://www.kernel.org/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.4

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

NVD Base Score: 5.5
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

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

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍