CVE Intelligence
Medium Memory corruption

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 Sep 11, 2025 · Updated Oct 19, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database, GitHub Security Advisories · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+1
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.18%
ahead of 7% of scored CVEs · Oct 19, 2026
Affects
Debian
Debian Linux and 2 more
CVSS base
5.5
Medium · 2 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Debian Debian Linux, Linux Linux, Linux Linux Kernel).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Debian Debian Linux version 11.0 Vulnerable NIST National Vulnerability Database
Linux Linux version 5.4≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < d1534ae23c2b6be350c8ab060803fbf6e9682adc≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < 9b80430c194e4a114dc663c1025d56b4f3d0153d≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < 926092268efdf1ed7b55cf486356c74a9e7710d1≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < 8d2d22a55ffe35c38e69795468a7addd1a80e9ce≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < e21a3ddd58733ce31afcb1e5dc3cb80a4b5bc29b≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < f014c10d190b92aad366e56b445daffcd1c075e4≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < a04de4c40aab9b338dfa989cf4aec70fd187eeb2
and 2 more ≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < 1ef72a7fedc5bca70e8cc980985790de10d407aa≥ 2abd839aa7e615f2bbc50c8ba7deb9e40d186768 and < 9f1f4e95031f84867c5821540466d62f88dab8ca
Vulnerable CVE Program (cve.org) e CISA ADP
Linux Linux Kernel version 5.4-rc7version 6.17-rc1version 5.4-rc8version 5.4-rc6version 5.4-rc5version 5.4-rc4version 5.4≥ 6.16 and < 6.16.2
and 7 more ≥ 6.13 and < 6.15.11≥ 6.7 and < 6.12.43≥ 6.2 and < 6.6.103≥ 5.16 and < 6.1.149≥ 5.11 and < 5.15.190≥ 5.5 and < 5.10.241≥ 5.4.1 and < 5.4.297
Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
5.5 CVSS 3.1 Medium 1.8 3.6 nvd@nist.gov via NIST National Vulnerability Database
5.5 CVSS 3.1 Medium — — GitHub, Inc. via GitHub Security Advisories
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-401 · Missing Release of Memory after Effective Lifetime

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Fix documented
    Oct 19, 2026 · NIST National Vulnerability Database
  • Affected products added · linux/linux kernel, debian/debian linux
    Oct 19, 2026 · NIST National Vulnerability Database
  • CVSS changed · 5.5
    Oct 19, 2026 · NIST National Vulnerability Database
  • Source status changed · Published → Modified
    Oct 19, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 19, 2026
  • Affected products added · linux/linux
    Oct 19, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 19, 2026 · CVE Program (cve.org) e CISA ADP
  • Record created in this database
    Oct 19, 2026 · Alertas do Telegram
  • 2025
  • CVE published
    Sep 11, 2025 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 3× References added · Oct 19, 2026 – Oct 19, 2026
  • 1× Official description updated · Oct 19, 2026 – Oct 19, 2026

References

14 on the record

Elsewhere on this site

Debian
every CVE for this vendor
Memory corruption
same class
CWE-401
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-98868 dm-pcache: reject a kset that overruns its segment 1d
  • CVE-2026-98866 sched/cache: Introduce task_struct->sched_cache_grp to fix UAF 1d
  • CVE-2026-98867 dm-pcache: bound the logical key offset from persistent memory 1d
  • CVE-2026-98865 sched_ext: Don't run ops.dequeue() with a DSQ lock held 1d
  • CVE-2026-98864 sched_ext: Wait for SCX_OPSS_DISPATCHING before reenqueueing a task 1d
  • CVE-2026-98863 KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said pages fails 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CISA SSVC assessment.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-39737 is "mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup()", rated Medium. It affects Debian Linux (Debian); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 0.18% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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