CVE-2025-21745: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: Fix class @block_class's subsystem refcount leakage blkcg_fill_root_iostats() iterates over @block_class's devices by class_dev_iter_(init|next)(), but does not end iterating with class_dev_iter_exit(), so causes the class's subsystem refcount leakage. Fix by ending the iterating with class_dev_iter_exit().

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.9 — 6.1.129
linux	linux_kernel	6.2 — 6.6.78
linux	linux_kernel	6.7 — 6.12.14
linux	linux_kernel	6.13 — 6.13.3

References

Advisories & Patches

https://git.kernel.org/stable/c/2ce09aabe009453d641a2ceb79e6461a2d4f3876 https://git.kernel.org/stable/c/431b6ef2714be4d5babb802114987541a88b43b0 https://git.kernel.org/stable/c/67c7f213e052b1aa6caba4a7e25e303bc6997126 https://git.kernel.org/stable/c/993121481b5a87829f1e8163f47158b72679f309 https://git.kernel.org/stable/c/d1248436cbef1f924c04255367ff4845ccd9025e

Other References

https://git.kernel.org/stable/c/38287f779b34dfe959b4b681e909f2d3d52b88be https://git.kernel.org/stable/c/ffb494f1e7a047bd7a41b13796fcfb08fe5beafb https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html https://cert-portal.siemens.com/productcert/html/ssa-082556.html https://cert-portal.siemens.com/productcert/html/ssa-265688.html

Frequently Asked Questions

What is CVE-2025-21745? +

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: Fix class @block_class's subsystem refcount leakage blkcg_fill_root_iostats() iterates over @block_class's devices by class_dev_iter_(init|next)(), but does not end iterating with class_dev_iter_exit(), so causes the class's subsystem refcount leakage. Fix by ending the iterating with class_dev_iter_exit(). It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21745? +

CVE-2025-21745 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-21745? +

CVE-2025-21745 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-21745? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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