Linux Kernel up to 6.6.99/6.12.39/6.15.7 net/rxrpc/recvmsg.c user_mutex race condition

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5.5$0-$5k0.00

Summaryinfo

A vulnerability marked as problematic has been reported in Linux Kernel up to 6.6.99/6.12.39/6.15.7. Affected by this issue is the function user_mutex of the file net/rxrpc/recvmsg.c. The manipulation leads to race condition. This vulnerability is uniquely identified as CVE-2025-38524. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.99/6.12.39/6.15.7 and classified as problematic. This issue affects the function user_mutex of the file net/rxrpc/recvmsg.c. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix recv-recv race of completed call If a call receives an event (such as incoming data), the call gets placed on the socket's queue and a thread in recvmsg can be awakened to go and process it. Once the thread has picked up the call off of the queue, further events will cause it to be requeued, and once the socket lock is dropped (recvmsg uses call->user_mutex to allow the socket to be used in parallel), a second thread can come in and its recvmsg can pop the call off the socket queue again. In such a case, the first thread will be receiving stuff from the call and the second thread will be blocked on call->user_mutex. The first thread can, at this point, process both the event that it picked call for and the event that the second thread picked the call for and may see the call terminate - in which case the call will be "released", decoupling the call from the user call ID assigned to it (RXRPC_USER_CALL_ID in the control message). The first thread will return okay, but then the second thread will wake up holding the user_mutex and, if it sees that the call has been released by the first thread, it will BUG thusly: kernel BUG at net/rxrpc/recvmsg.c:474! Fix this by just dequeuing the call and ignoring it if it is seen to be already released. We can't tell userspace about it anyway as the user call ID has become stale.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2025-38524 since 04/16/2025. The exploitation is known to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 265749 (SUSE SLED15 / SLES15 Security Update : kernel (SUSE-SU-2025:03290-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.100, 6.12.40 or 6.15.8 eliminates this vulnerability. Applying the patch 7692bde890061797f3dece0148d7859e85c55778/839fe96c15209dc2255c064bb44b636efe04f032/6c75a97a32a5fa2060c3dd30207e63b6914b606d/962fb1f651c2cf2083e0c3ef53ba69e3b96d3fbc 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 (265749), EUVD (EUVD-2025-27883) and CERT Bund (WID-SEC-2025-1858). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Dell Avamar
  • Open Source Linux Kernel
  • Dell NetWorker
  • Dell Secure Connect Gateway
  • IBM QRadar SIEM
  • IBM Security Verify Access

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

VulDB Base Score: 4.6
VulDB Temp Score: 4.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.7
NVD Vector: 🔒

CNA Base Score: 7.5
CNA Vector (Linux): 🔒

CVSSv2info

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

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 265749
Nessus Name: SUSE SLED15 / SLES15 Security Update : kernel (SUSE-SU-2025:03290-1)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.100/6.12.40/6.15.8
Patch: 7692bde890061797f3dece0148d7859e85c55778/839fe96c15209dc2255c064bb44b636efe04f032/6c75a97a32a5fa2060c3dd30207e63b6914b606d/962fb1f651c2cf2083e0c3ef53ba69e3b96d3fbc

Timelineinfo

04/16/2025 CVE reserved
08/16/2025 +122 days Advisory disclosed
08/16/2025 +0 days VulDB entry created
08/01/2026 +350 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38524 (🔒)
GCVE (CVE): GCVE-0-2025-38524
GCVE (VulDB): GCVE-100-320387
EUVD: 🔒
CERT Bund: WID-SEC-2025-1858 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 08/16/2025 14:37
Updated: 08/01/2026 20:03
Changes: 08/16/2025 14:37 (58), 08/19/2025 10:17 (1), 09/24/2025 04:31 (2), 09/28/2025 08:53 (7), 10/03/2025 10:44 (1), 10/12/2025 18:03 (1), 11/01/2025 19:49 (1), 11/19/2025 01:37 (10), 11/19/2025 03:53 (1), 01/30/2026 18:27 (1), 08/01/2026 20:03 (13)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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