CVE-2025-39737 | mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup()

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.

Published: 2025-09-11 Last update: 2026-05-12 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-39737 is rated Low Risk (23.7/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.02%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-39737

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-01-29 0.06% 0.02% -0.04%
2 2026-01-11 0.03% 0.06% +0.03%
3 2025-09-12 — 0.03% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-39737

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 3.6 [email protected]

Weakness enumeration for CVE-2025-39737

GitHub Security Advisory for CVE-2025-39737

GHSA-x37q-qw63-qf28 · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid soft...

OS Trackers for CVE-2025-39737

vendor priority summary link
debian not yet assigned CVE-2025-39737 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2025-39737
redhat low — https://access.redhat.com/security/cve/CVE-2025-39737
suse low — https://www.suse.com/security/cve/CVE-2025-39737/
ubuntu medium CVE-2025-39737 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1414 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): DNE 1017, ignored 180, released 150, needed 48, not-affected 16, needs-triage 2, pending 1. https://ubuntu.com/security/CVE-2025-39737

Affected software / configurations for CVE-2025-39737

Vendor Product Version Raw CPE
linux linux_kernel >= 5.4.1, < 5.4.297 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.5, < 5.10.241 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.190 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.149 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.103 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.43 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.15.11 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.16, < 6.16.2 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 5.4 cpe:2.3:o:linux:linux_kernel:5.4:-:*:*:*:*:*:*
linux linux_kernel 5.4 cpe:2.3:o:linux:linux_kernel:5.4:rc4:*:*:*:*:*:*
linux linux_kernel 5.4 cpe:2.3:o:linux:linux_kernel:5.4:rc5:*:*:*:*:*:*
linux linux_kernel 5.4 cpe:2.3:o:linux:linux_kernel:5.4:rc6:*:*:*:*:*:*
linux linux_kernel 5.4 cpe:2.3:o:linux:linux_kernel:5.4:rc7:*:*:*:*:*:*
linux linux_kernel 5.4 cpe:2.3:o:linux:linux_kernel:5.4:rc8:*:*:*:*:*:*
linux linux_kernel 6.17 cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2025-39737

URL Tags
https://git.kernel.org/stable/c/1ef72a7fedc5bca70e8cc980985790de10d407aa Patch
https://git.kernel.org/stable/c/8d2d22a55ffe35c38e69795468a7addd1a80e9ce Patch
https://git.kernel.org/stable/c/926092268efdf1ed7b55cf486356c74a9e7710d1 Patch
https://git.kernel.org/stable/c/9b80430c194e4a114dc663c1025d56b4f3d0153d Patch
https://git.kernel.org/stable/c/9f1f4e95031f84867c5821540466d62f88dab8ca Patch
https://git.kernel.org/stable/c/a04de4c40aab9b338dfa989cf4aec70fd187eeb2 Patch
https://git.kernel.org/stable/c/d1534ae23c2b6be350c8ab060803fbf6e9682adc Patch
https://git.kernel.org/stable/c/e21a3ddd58733ce31afcb1e5dc3cb80a4b5bc29b Patch
https://git.kernel.org/stable/c/f014c10d190b92aad366e56b445daffcd1c075e4 Patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Mailing List Third Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-032379.html
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