CVE-2025-39737

Published Sep 11, 2025

Last updated 4 days ago

CVSS medium 5.5

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup() A soft lockup warning was observed on a relative small system x86-64 system with 16 GB of memory when running a debug kernel with kmemleak enabled. watchdog: BUG: soft lockup - CPU#8 stuck for 33s! [kworker/8:1:134] The test system was running a workload with hot unplug happening in parallel. Then kemleak decided to disable itself due to its inability to allocate more kmemleak objects. The debug kernel has its CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE set to 40,000. The soft lockup happened in kmemleak_do_cleanup() when the existing kmemleak objects were being removed and deleted one-by-one in a loop via a workqueue. In this particular case, there are at least 40,000 objects that need to be processed and given the slowness of a debug kernel and the fact that a raw_spinlock has to be acquired and released in __delete_object(), it could take a while to properly handle all these objects. As kmemleak has been disabled in this case, the object removal and deletion process can be further optimized as locking isn't really needed. However, it is probably not worth the effort to optimize for such an edge case that should rarely happen. So the simple solution is to call cond_resched() at periodic interval in the iteration loop to avoid soft lockup.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel, debian_linux

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
CWE-401

Social media

Hype score
Not currently trending

  1. [CVE Analysis] CVE-2025-39737: SIMATIC CN 4100 Multiple Memory Corruption Flaws Below Version 5.0 https://t.co/tqHis05zhg #ICS #OTSecurity #SCADA #CriticalInfrastructure

    @breachspider

    11 Jul 2026

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  2. CVE-2025-39737 In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup() A soft lockup warning was observed on … https://t.co/21OMsG0zk1

    @CVEnew

    11 Sept 2025

    368 Impressions

    0 Retweets

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Configurations

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References

Sources include official advisories and independent security research.