Linux Kernel up to 6.17.5 ocfs2 ocfs2_refcount_cal_cow_clusters reference count

CVSS Meta Temp Score
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CTI Interest Score
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5.5$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 6.17.5. Affected is the function ocfs2_refcount_cal_cow_clusters of the component ocfs2. The manipulation leads to reference count. This vulnerability is traded as CVE-2025-40233. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.17.5. This issue affects the function ocfs2_refcount_cal_cow_clusters of the component ocfs2. The manipulation with an unknown input leads to a reference count vulnerability. Using CWE to declare the problem leads to CWE-911. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ocfs2: clear extent cache after moving/defragmenting extents The extent map cache can become stale when extents are moved or defragmented, causing subsequent operations to see outdated extent flags. This triggers a BUG_ON in ocfs2_refcount_cal_cow_clusters(). The problem occurs when: 1. copy_file_range() creates a reflinked extent with OCFS2_EXT_REFCOUNTED 2. ioctl(FITRIM) triggers ocfs2_move_extents() 3. __ocfs2_move_extents_range() reads and caches the extent (flags=0x2) 4. ocfs2_move_extent()/ocfs2_defrag_extent() calls __ocfs2_move_extent() which clears OCFS2_EXT_REFCOUNTED flag on disk (flags=0x0) 5. The extent map cache is not invalidated after the move 6. Later write() operations read stale cached flags (0x2) but disk has updated flags (0x0), causing a mismatch 7. BUG_ON(!(rec->e_flags & OCFS2_EXT_REFCOUNTED)) triggers Fix by clearing the extent map cache after each extent move/defrag operation in __ocfs2_move_extents_range(). This ensures subsequent operations read fresh extent data from disk.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2025-40233 since 04/16/2025. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 277493 (Linux Distros Unpatched Vulnerability : CVE-2025-40233), 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, 6.6.115, 6.12.56 or 6.17.6 eliminates this vulnerability. Applying the patch 93166bc53c0e3587058327a4121daea34b4fecd5/a7ee72286efba1d407c6f15a0528e43593fb7007/93b1ab422f1966b71561158e1aedce4ec100f357/e92af7737a94a729225d2a5d180eaaa77fe0bbc1/aa6a21409dd6221bb268b56bb410e031c632ff9a/bb69928ed578f881e68d26aaf1a8f6e7faab3b44/a21750df2f6169af6e039a3bb4893d6c9564e48d/78a63493f8e352296dbc7cb7b3f4973105e8679e 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 (277493) and CERT Bund (WID-SEC-2025-2747). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Debian Linux
  • Google Cloud Platform
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux
  • Microsoft Azure Linux

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.7
VulDB Meta Temp Score: 5.5

VulDB Base Score: 5.7
VulDB Temp Score: 5.5
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: Reference count
CWE: CWE-911 / CWE-664
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: 277493
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-40233

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.4.301/5.10.246/5.15.196/6.1.158/6.6.115/6.12.56/6.17.6
Patch: 93166bc53c0e3587058327a4121daea34b4fecd5/a7ee72286efba1d407c6f15a0528e43593fb7007/93b1ab422f1966b71561158e1aedce4ec100f357/e92af7737a94a729225d2a5d180eaaa77fe0bbc1/aa6a21409dd6221bb268b56bb410e031c632ff9a/bb69928ed578f881e68d26aaf1a8f6e7faab3b44/a21750df2f6169af6e039a3bb4893d6c9564e48d/78a63493f8e352296dbc7cb7b3f4973105e8679e

Timelineinfo

04/16/2025 CVE reserved
12/04/2025 +232 days Advisory disclosed
12/04/2025 +0 days VulDB entry created
02/23/2026 +81 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40233 (🔒)
GCVE (CVE): GCVE-0-2025-40233
GCVE (VulDB): GCVE-100-334289
CERT Bund: WID-SEC-2025-2747 - Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 12/04/2025 17:29
Updated: 02/23/2026 19:18
Changes: 12/04/2025 17:29 (59), 12/06/2025 20:17 (2), 01/05/2026 01:36 (7), 02/23/2026 19:18 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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