Linux Kernel up to 6.18.1 hfs_correct_next_unused_CNID use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.6$0-$5k0.00

Summaryinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.18.1. Affected by this issue is the function hfs_correct_next_unused_CNID. The manipulation leads to use after free. This vulnerability is uniquely identified as CVE-2025-68761. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.18.1. This issue affects the function hfs_correct_next_unused_CNID. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: hfs: fix potential use after free in hfs_correct_next_unused_CNID() This code calls hfs_bnode_put(node) which drops the refcount and then dreferences "node" on the next line. It's only safe to use "node" when we're holding a reference so flip these two lines around.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2025-68761 since 12/24/2025. The exploitation is known to be easy. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 01/08/2026).

The vulnerability scanner Nessus provides a plugin with the ID 281914 (Linux Distros Unpatched Vulnerability : CVE-2025-68761), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.18.2 or 6.19-rc1 eliminates this vulnerability. Applying the patch 40a1e0142096dd7dd6cb5373841222b528698588/c105e76bb17cf4b55fe89c6ad4f6a0e3972b5b08 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 (281914) and CERT Bund (WID-SEC-2026-0009). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Microsoft Azure Linux
  • Open Source Linux Kernel

Productinfo

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Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.6

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
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: Use after free
CWE: CWE-416 / CWE-119
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: 281914
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-68761

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.2/6.19-rc1
Patch: 40a1e0142096dd7dd6cb5373841222b528698588/c105e76bb17cf4b55fe89c6ad4f6a0e3972b5b08

Timelineinfo

12/24/2025 CVE reserved
01/05/2026 +12 days Advisory disclosed
01/05/2026 +0 days VulDB entry created
01/08/2026 +3 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-68761 (🔒)
GCVE (CVE): GCVE-0-2025-68761
GCVE (VulDB): GCVE-100-339527
CERT Bund: WID-SEC-2026-0009 - Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 01/05/2026 11:12
Updated: 01/08/2026 17:35
Changes: 01/05/2026 11:12 (58), 01/06/2026 08:54 (7), 01/07/2026 17:05 (2), 01/08/2026 17:35 (1)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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