Linux Kernel: NULL Pointer Dereference (CVE-2025-21744)
Published Last modified Sources: Siemens ProductCERT, BSI, SUSE, Debian LTS, CVE.org, Msrc Update Guide, EUVD
What is affected, what to do
In the Linux kernel, the following vulnerability has been resolved: wifi: brcmfmac: fix NULL pointer dereference in brcmf_txfinalize() On removal of the device or unloading of the kernel module a potential NULL pointer dereference occurs. The following sequence deletes the interface: brcmf_detach() brcmf_remove_interface() brcmf_del_if() Inside the brcmf_del_if() function the drvr->if2bss[ifidx] is updated to BRCMF_BSSIDX_INVALID (-1) if the bsscfgidx matches.
The available sources name no fixed version. Check the vendor guidance in the references below.
Conflicting version data — version display is hidden until the data is resolved.
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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, CVE.org, Msrc Update Guide, EUVD
0.3 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 17.0
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- 37.82 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- 17.0
- 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: wifi: brcmfmac: fix NULL pointer dereference in brcmf_txfinalize() On removal of the device or unloading of the kernel module a potential NULL pointer dereference occurs. The following sequence deletes the interface: brcmf_detach() brcmf_remove_interface() brcmf_del_if() Inside the brcmf_del_if() function the drvr->if2bss[ifidx] is updated to BRCMF_BSSIDX_INVALID (-1) if the bsscfgidx matches. After brcmf_remove_interface() call the brcmf_proto_detach() function is called providing the following sequence: brcmf_detach() brcmf_proto_detach() brcmf_proto_msgbuf_detach() brcmf_flowring_detach() brcmf_msgbuf_delete_flowring() brcmf_msgbuf_remove_flowring() brcmf_flowring_delete() brcmf_get_ifp() brcmf_txfinalize() Since brcmf_get_ip() can and actually will return NULL in this case the call to brcmf_txfinalize() will result in a NULL pointer dereference inside brcmf_txfinalize() when trying to update ifp->ndev->stats.tx_errors. This will only happen if a flowring still has an skb. Although the NULL pointer dereference has only been seen when trying to update the tx statistic, all other uses of the ifp pointer have been guarded as well with an early return if ifp is NULL.
Source: siemens_advisory, BSI CSAF, BSI WID Portal, suse_csaf, Debian LTS Advisories, cvelistv5, NVD (NIST), Microsoft Security Update Guide, CVE.org (MITRE), ENISA EUVD
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 |
|
|
| 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/2326e19190e176fd72bb542b837a9d2b7fcb8693
- git.kernel.orgstable/c/59ff4fa653ff6db07c61152516ffba79c2a74bda
- git.kernel.orgstable/c/61541d9b5a23df33934fcc620a3a81f246b1b240
- git.kernel.orgstable/c/4e51d6d093e763348916e69d06d87e0a5593661b
- git.kernel.orgstable/c/3877fc67bd3d5566cc12763bce39710ceb74a97d
- git.kernel.orgstable/c/fbbfef2a5b858eab55741a58b2ac9a0cc8d53c58
- git.kernel.orgstable/c/a2beefc4fa49ebc22e664dc6b39dbd054f8488f9
- git.kernel.orgstable/c/68abd0c4ebf24cd499841a488b97a6873d5efabb
- 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-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/2326e19190e176fd72bb542b837a9d2b7fcb8693
- https://git.kernel.org/stable/c/3877fc67bd3d5566cc12763bce39710ceb74a97d
- https://git.kernel.org/stable/c/4e51d6d093e763348916e69d06d87e0a5593661b
- https://git.kernel.org/stable/c/59ff4fa653ff6db07c61152516ffba79c2a74bda
and 4 more references
Show 21 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://git.kernel.org/stable/c/2326e19190e176fd72bb542b837a9d2b7fcb8693Reference added —https://git.kernel.org/stable/c/3877fc67bd3d5566cc12763bce39710ceb74a97dReference added —https://git.kernel.org/stable/c/4e51d6d093e763348916e69d06d87e0a5593661bReference added —https://git.kernel.org/stable/c/59ff4fa653ff6db07c61152516ffba79c2a74bdaReference added —https://git.kernel.org/stable/c/61541d9b5a23df33934fcc620a3a81f246b1b240Reference added —https://git.kernel.org/stable/c/68abd0c4ebf24cd499841a488b97a6873d5efabbReference added —https://git.kernel.org/stable/c/a2beefc4fa49ebc22e664dc6b39dbd054f8488f9Reference added —https://git.kernel.org/stable/c/fbbfef2a5b858eab55741a58b2ac9a0cc8d53c58Reference removed https://git.kernel.org/stable/c/2326e19190e176fd72bb542b837a9d2b7fcb8693—Reference removed https://git.kernel.org/stable/c/3877fc67bd3d5566cc12763bce39710ceb74a97d—Reference removed https://git.kernel.org/stable/c/4e51d6d093e763348916e69d06d87e0a5593661b—Reference removed https://git.kernel.org/stable/c/59ff4fa653ff6db07c61152516ffba79c2a74bda—Reference removed https://git.kernel.org/stable/c/61541d9b5a23df33934fcc620a3a81f246b1b240—Reference removed https://git.kernel.org/stable/c/68abd0c4ebf24cd499841a488b97a6873d5efabb—Reference removed https://git.kernel.org/stable/c/a2beefc4fa49ebc22e664dc6b39dbd054f8488f9—Reference removed https://git.kernel.org/stable/c/fbbfef2a5b858eab55741a58b2ac9a0cc8d53c58—Reference type removed https://git.kernel.org/stable/c/3877fc67bd3d5566cc12763bce39710ceb74a97d Types: Patch—Reference type removed https://git.kernel.org/stable/c/4e51d6d093e763348916e69d06d87e0a5593661b Types: Patch—Reference type removed https://git.kernel.org/stable/c/68abd0c4ebf24cd499841a488b97a6873d5efabb Types: Patch—Reference type removed https://git.kernel.org/stable/c/a2beefc4fa49ebc22e664dc6b39dbd054f8488f9 Types: Patch—Reference type removed https://git.kernel.org/stable/c/fbbfef2a5b858eab55741a58b2ac9a0cc8d53c58 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 4 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-2025-21744.json">CVE-2025-21744</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-265688.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-784472.htmlReference 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-2025-21744"><img src="https://intel.neosec.eu/badge/cve/CVE-2025-21744.svg?lang=en" alt="CVE-2025-21744 – NEOSEC Intel" height="20"></a>