CVE-2025-39953: Linux kernel · cgroup: split cgroup_destroy_wq into 3 workqueues
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in f2795d1b92506e3adf52a298f7181032a1525e04 : update Linux kernel when convenient.
Data as of 10 Nov 2026, 12:50 UTC
Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-06-10.
- Patch
- Available – fixed in f2795d1b92506e3adf52a298f7181032a1525e04, ded4d207a3209a834b6831ceec7f39b934c74802, cabadd7fd15f97090f752fd22dd7f876a0dc3dc4 +5
Exploitation evidence
Disclosed: evidence found.
CVE published 4 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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AI-suggested
A fix is available and has been applied in the Linux kernel. The vulnerability is resolved by splitting the cgroup_destroy_wq workqueue into three dedicated workqueues to eliminate blocking and hangs. Users should update to a Linux kernel version that includes the fix (commits listed in establishedFacts.fixedVersions). No additional mitigation is required beyond applying the official fix.
Description
A Linux kernel vulnerability (CVE-2025-39953) involves a hang condition during cgroup root destruction when repeatedly mounting and unmounting perf_event and net_prio controllers with systemd.unified_cgroup_hierarchy=1. The issue arises from a single workqueue (cgroup_destroy_wq) handling multiple tasks, causing blocking and a hung task during cgroup destruction. The fix splits this workqueue into three dedicated workqueues to prevent blocking and hangs.
References
- git.kernel.org/stable/c/cabadd7fd15f97090f752fd22dd7f876a0dc3dc4 (opens in a new tab)
- git.kernel.org/stable/c/a0c896bda7077aa5005473e2c5b3c27173313b4c (opens in a new tab)
- git.kernel.org/stable/c/f2795d1b92506e3adf52a298f7181032a1525e04 (opens in a new tab)
- git.kernel.org/stable/c/993049c9b1355c78918344a6403427d53f9ee700 (opens in a new tab)
- git.kernel.org/stable/c/4a1e3ec28e8062cd9f339aa6a942df9c5bcb6811 (opens in a new tab)
- git.kernel.org/stable/c/ded4d207a3209a834b6831ceec7f39b934c74802 (opens in a new tab)
- git.kernel.org/stable/c/05e0b03447cf215ec384210441b34b7a3b16e8b0 (opens in a new tab)
- git.kernel.org/stable/c/79f919a89c9d06816dbdbbd168fa41d27411a7f9 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)