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CVE-2025-39736

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock When netpoll is enabled, calling pr_warn_once() while hol…

Published Sep 11, 2025CWE-667EPSS 0.13%

Overview

CVE-2025-39736 is a medium-severity vulnerability. It was published on September 11, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock

When netpoll is enabled, calling pr_warn_once() while holding

kmemleak_lock in mem_pool_alloc() can cause a deadlock due to lock

inversion with the netconsole subsystem. This occurs because

pr_warn_once() may trigger netpoll, which eventually leads to

__alloc_skb() and back into kmemleak code, attempting to reacquire

kmemleak_lock.

This is the path for the deadlock.

mem_pool_alloc()

-> raw_spin_lock_irqsave(&kmemleak_lock, flags);

-> pr_warn_once()

-> netconsole subsystem

-> netpoll

-> __alloc_skb

-> __create_object

-> raw_spin_lock_irqsave(&kmemleak_lock, flags);

Fix this by setting a flag and issuing the pr_warn_once() after

kmemleak_lock is released.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/08f70be5e406ce47c822f2dd11c1170ca259605bRefgit.kernel.org/stable/c/1da95d3d4b7b1d380ebd87b71a61e7e6aed3265dRefgit.kernel.org/stable/c/47b0f6d8f0d2be4d311a49e13d2fd5f152f492b2Refgit.kernel.org/stable/c/4b0151e1d468eb2667c37b7af99b3c075072d334Refgit.kernel.org/stable/c/62879faa8efe8d8a9c7bf7606ee9c068012d7dacRefgit.kernel.org/stable/c/a0854de00ce2ee27edf39037e7836ad580eb3350Refgit.kernel.org/stable/c/a181b228b37a6a5625dad2bb4265bb7abb673e9fRefgit.kernel.org/stable/c/c7b6ea0ede687e7460e593c5ea478f50aa41682aRefgit.kernel.org/stable/c/f249d32bb54876b4b6c3ae071af8ddca77af390bReflists.debian.org/debian-lts-announce/2025/10/msg00007.html

How CyberStrike helps

Frequently asked questions

What is CVE-2025-39736?

CVE-2025-39736 is a medium-severity vulnerability. It was published on September 11, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-39736?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-39736?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-39736?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-39736 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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