Linux Kernel: Memory Leak (CVE-2025-21745)
Published Last modified Sources: Siemens ProductCERT, BSI, SUSE, Debian LTS, Red Hat, CVE.org, EUVD, Msrc Update Guide
What is affected, what to do
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().
Update Linux Kernel to version 5.10.235, Linux Kernel to version 5.15.179, Linux Kernel to version 6.1.129.
- Affected
- Linux Kernel
lt 5.9..5.10.235 - Linux Kernel
lt 5.11..5.15.179 - Linux Kernel
lt 5.16..6.1.129 - Linux Kernel
lt 6.2..6.6.78 - Linux Kernel
lt 6.7..6.12.14 - Linux Kernel
lt 6.13..6.13.3
- Linux Kernel
- Fixed in
- Linux Kernel
5.10.235 - Linux Kernel
5.15.179 - Linux Kernel
6.1.129 - Linux Kernel
6.6.78 - Linux Kernel
6.12.14 - Linux Kernel
6.13.3 - Linux Kernel
6.14
- Linux Kernel
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Metrics
5.5
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
5.5
CVSS v3
Severity Medium on the scale from 0 to 10.
Source: Siemens ProductCERT, BSI, SUSE, Debian LTS, Red Hat, CVE.org, EUVD, Msrc Update Guide
0.3 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 18.8
Show all metrics
- Severity
- Medium
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 38.31 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 5.5 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 5.5
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.3 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 18.8
- Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
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().
Source: siemens_advisory, BSI WID Portal, BSI CSAF, suse_csaf, Debian LTS Advisories, redhat_csaf, NVD (NIST), CVE.org (MITRE), ENISA EUVD, cvelistv5, Microsoft Security Update Guide
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Linux | Linux |
|
|
| Dell | Secure Connect Gateway |
|
|
| IBM | Security Verify Access |
|
|
| Siemens | SIMATIC S7 |
|
|
Vendors and products
Affected operating systems
| Linux | debian | linux | bullseye |
| Linux | debian | linux-6.1 | bullseye |
| Linux | linux | linux_kernel | — |
References & sources
- git.kernel.orgstable/c/ffb494f1e7a047bd7a41b13796fcfb08fe5beafb
- git.kernel.orgstable/c/38287f779b34dfe959b4b681e909f2d3d52b88be
- git.kernel.orgstable/c/431b6ef2714be4d5babb802114987541a88b43b0
- git.kernel.orgstable/c/993121481b5a87829f1e8163f47158b72679f309
- git.kernel.orgstable/c/2ce09aabe009453d641a2ceb79e6461a2d4f3876
- git.kernel.orgstable/c/67c7f213e052b1aa6caba4a7e25e303bc6997126
- git.kernel.orgstable/c/d1248436cbef1f924c04255367ff4845ccd9025e
- lists.debian.orgdebian-lts-announce/2025/05/msg00030.html
- lists.debian.orgdebian-lts-announce/2025/03/msg00028.html
- Siemens ProductCERTproductcert/html/ssa-265688.html
- Siemens ProductCERTproductcert/html/ssa-082556.html
- Siemens ProductCERTproductcert/html/ssa-019113.html
- Siemens ProductCERTproductcert/html/ssa-457936.html
- Siemens ProductCERTproductcert/html/ssa-784472.html
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedLinux
New references:- https://git.kernel.org/stable/c/2ce09aabe009453d641a2ceb79e6461a2d4f3876
- https://git.kernel.org/stable/c/38287f779b34dfe959b4b681e909f2d3d52b88be
- https://git.kernel.org/stable/c/431b6ef2714be4d5babb802114987541a88b43b0
- https://git.kernel.org/stable/c/67c7f213e052b1aa6caba4a7e25e303bc6997126
and 3 more references
Show 19 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://git.kernel.org/stable/c/2ce09aabe009453d641a2ceb79e6461a2d4f3876Reference added —https://git.kernel.org/stable/c/38287f779b34dfe959b4b681e909f2d3d52b88beReference added —https://git.kernel.org/stable/c/431b6ef2714be4d5babb802114987541a88b43b0Reference added —https://git.kernel.org/stable/c/67c7f213e052b1aa6caba4a7e25e303bc6997126Reference added —https://git.kernel.org/stable/c/993121481b5a87829f1e8163f47158b72679f309Reference added —https://git.kernel.org/stable/c/d1248436cbef1f924c04255367ff4845ccd9025eReference added —https://git.kernel.org/stable/c/ffb494f1e7a047bd7a41b13796fcfb08fe5beafbReference removed https://git.kernel.org/stable/c/2ce09aabe009453d641a2ceb79e6461a2d4f3876—Reference removed https://git.kernel.org/stable/c/38287f779b34dfe959b4b681e909f2d3d52b88be—Reference removed https://git.kernel.org/stable/c/431b6ef2714be4d5babb802114987541a88b43b0—Reference removed https://git.kernel.org/stable/c/67c7f213e052b1aa6caba4a7e25e303bc6997126—Reference removed https://git.kernel.org/stable/c/993121481b5a87829f1e8163f47158b72679f309—Reference removed https://git.kernel.org/stable/c/d1248436cbef1f924c04255367ff4845ccd9025e—Reference removed https://git.kernel.org/stable/c/ffb494f1e7a047bd7a41b13796fcfb08fe5beafb—Reference type removed https://git.kernel.org/stable/c/2ce09aabe009453d641a2ceb79e6461a2d4f3876 Types: Patch—Reference type removed https://git.kernel.org/stable/c/431b6ef2714be4d5babb802114987541a88b43b0 Types: Patch—Reference type removed https://git.kernel.org/stable/c/67c7f213e052b1aa6caba4a7e25e303bc6997126 Types: Patch—Reference type removed https://git.kernel.org/stable/c/993121481b5a87829f1e8163f47158b72679f309 Types: Patch—Reference type removed https://git.kernel.org/stable/c/d1248436cbef1f924c04255367ff4845ccd9025e Types: Patch—Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Record modifiedCVE Program
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://lists.debian.org/debian-lts-announce/2025/03/msg00028.htmlReference added —https://lists.debian.org/debian-lts-announce/2025/05/msg00030.htmlReference removed https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html—Reference removed https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html—Source identifier: af854a3a-2127-422b-91ae-364da2661108
Record modifiedSiemens ADP
Show 9 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2025/21xxx/CVE-2025-21745.json">CVE-2025-21745</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-019113.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-082556.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-265688.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-457936.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-784472.htmlReference removed https://cert-portal.siemens.com/productcert/html/ssa-019113.html—Reference removed https://cert-portal.siemens.com/productcert/html/ssa-082556.html—Reference removed https://cert-portal.siemens.com/productcert/html/ssa-265688.html—Source identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
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<a href="https://intel.neosec.eu/en/cve/CVE-2025-21745"><img src="https://intel.neosec.eu/badge/cve/CVE-2025-21745.svg?lang=en" alt="CVE-2025-21745 – NEOSEC Intel" height="20"></a>