CVE-2025-21745: Linux kernel · blk-cgroup: Fix class @block_class's subsystem refcount leakage
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 10 Nov 2026, 14:48 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or noneExploitation evidence
Disclosed: evidence found.
CVE published 27 Feb 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
AI-suggested
A fix is available that corrects the iteration process by adding the missing class_dev_iter_exit() call. Users should apply the official Linux kernel update that includes this fix to resolve the reference count leakage.
Description
A vulnerability in the Linux kernel's blk-cgroup subsystem caused a subsystem reference count leakage due to improper iteration handling over block devices. The issue was fixed by ensuring the iteration ends correctly with class_dev_iter_exit().
References
- git.kernel.org/stable/c/ffb494f1e7a047bd7a41b13796fcfb08fe5beafb (opens in a new tab)
- git.kernel.org/stable/c/38287f779b34dfe959b4b681e909f2d3d52b88be (opens in a new tab)
- git.kernel.org/stable/c/431b6ef2714be4d5babb802114987541a88b43b0 (opens in a new tab)
- git.kernel.org/stable/c/993121481b5a87829f1e8163f47158b72679f309 (opens in a new tab)
- git.kernel.org/stable/c/2ce09aabe009453d641a2ceb79e6461a2d4f3876 (opens in a new tab)
- git.kernel.org/stable/c/67c7f213e052b1aa6caba4a7e25e303bc6997126 (opens in a new tab)
- git.kernel.org/stable/c/d1248436cbef1f924c04255367ff4845ccd9025e (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00030.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/03/msg00028.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-265688.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (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)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)