CVE-2025-39737: mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup()
Vulnerability summary
CVE-2025-39737 is a medium (CVSS 5.5) vulnerability in debian debian_linux. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.1% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 28 · Related 25Timeline
- 11-09-2025PublishedVulnerability first disclosed.
- 12-05-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.18%
Chance of exploitation in the next 30 days
Percentile
7%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.18% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu149 products
- linuxAll versions (No fix recorded) | < 5.15.0-163.173 | < 6.8.0-100.100
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1097.104 | < 6.8.0-1046.49
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Debian2 products
- linux< 6.1.153-1 | < 6.12.43-1 | < 6.16.3-1
- debian_linuxEOL11.0
Linux2 products
- linux≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < 9f1f4e95031f84867c5821540466d62f88dab8ca | ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < 1ef72a7fedc5bca70e8cc980985790de10d407aa | ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < a04de4c40aab9b338dfa989cf4aec70fd187eeb2 | ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < f014c10d190b92aad366e56b445daffcd1c075e4 | ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < e21a3ddd58733ce31afcb1e5dc3cb80a4b5bc29b | ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < 8d2d22a55ffe35c38e69795468a7addd1a80e9ce | ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < 926092268efdf1ed7b55cf486356c74a9e7710d1 | ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < 9b80430c194e4a114dc663c1025d56b4f3d0153d | ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768, < d1534ae23c2b6be350c8ab060803fbf6e9682adc | 5.4
- linux_kernelEOL≥ 5.4.1, < 5.4.297 | ≥ 5.5, < 5.10.241 | ≥ 5.11, < 5.15.190 | ≥ 5.16, < 6.1.149 | ≥ 6.2, < 6.6.103 | ≥ 6.7, < 6.12.43 | ≥ 6.13, < 6.15.11 | ≥ 6.16, < 6.16.2 | 5.4 | 5.4:rc4 | 5.4:rc5 | 5.4:rc6 | 5.4:rc7 | 5.4:rc8 | 6.17:rc1
3 vendors · 153 products
