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Linux KernelOperating system · Linux

CVE-2025-21744

MEDIUM · 5.5 CVSS v3.1 Published 2025-02-27
Fix available
A fix is available. Upgrade to 6.1.129 / 6.6.78 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:< 6.1.129>= 6.2, < 6.6.78>= 6.7, < 6.12.14>= 6.13, < 6.13.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.1.129 / 6.6.78 / 6.12.14 or later
Fixed in 6.1.1296.6.786.12.14
Vendor patch git.kernel.org →
Recommended fix High confidence

6.1.129, 6.6.78, 6.12.14, or 6.13.3 (depending on which stable branch you are on)

  1. Upgrade the Linux kernel to version 6.1.129 or later if currently running < 6.1.129
  2. If running kernel >= 6.2 but < 6.6.78, upgrade to 6.6.78 or later
  3. If running kernel >= 6.7 but < 6.12.14, upgrade to 6.12.14 or later
  4. If running kernel >= 6.13 but < 6.13.3, upgrade to 6.13.3 or later
  5. After kernel upgrade, reboot the system to load the fixed kernel version
  6. For embedded systems or modules, ensure the brcmfmac kernel module is rebuilt against the new kernel
Caveat Standard kernel upgrade risks apply - ensure compatibility with userspace tools and drivers; some kernel configurations may need adjustment

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-21744 in production — separate from our analysis above.

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