# CVE-2025-21750: wifi: brcmfmac: Check the return value of of_property_read_string_index()

> A missing return value check in the brcmfmac WiFi driver causes a kernel crash when a specific device tree property is missing.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Feb 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-68976, BELL-CVE-2025-21750, DEBIAN-CVE-2025-21750, GHSA-6m6q-fm24-h726, ROOT-OS-DEBIAN-11-CVE-2025-21750, ROOT-OS-UBUNTU-2204-CVE-2025-21750, ROOT-OS-UBUNTU-2404-CVE-2025-21750, UBUNTU-CVE-2025-21750

## What is CVE-2025-21750?

CVE-2025-21750 is a medium-severity vulnerability in Linux kernel, published on 27 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

wifi: brcmfmac: Check the return value of of_property_read_string_index()

Somewhen between 6.10 and 6.11 the driver started to crash on my
MacBookPro14,3. The property doesn't exist and 'tmp' remains
uninitialized, so we pass a random pointer to devm_kstrdup().

The crash I am getting looks like this:

BUG: unable to handle page fault for address: 00007f033c669379
PF: supervisor read access in kernel mode
PF: error_code(0x0001) - permissions violation
PGD 8000000101341067 P4D 8000000101341067 PUD 101340067 PMD 1013bb067 PTE 800000010aee9025
Oops: Oops: 0001 [#1] SMP PTI
CPU: 4 UID: 0 PID: 827 Comm: (udev-worker) Not tainted 6.11.8-gentoo #1
Hardware name: Apple Inc. MacBookPro14,3/Mac-551B86E5744E2388, BIOS 529.140.2.0.0 06/23/2024
RIP: 0010:strlen+0x4/0x30
Code: f7 75 ec 31 c0 c3 cc cc cc cc 48 89 f8 c3 cc cc cc cc 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <80> 3f 00 74 14 48 89 f8 48 83 c0 01 80 38 00 75 f7 48 29 f8 c3 cc
RSP: 0018:ffffb4aac0683ad8 EFLAGS: 00010202
RAX: 00000000ffffffea RBX: 00007f033c669379 RCX: 0000000000000001
RDX: 0000000000000cc0 RSI: 00007f033c669379 RDI: 00007f033c669379
RBP: 00000000ffffffea R08: 0000000000000000 R09: 00000000c0ba916a
R10: ffffffffffffffff R11: ffffffffb61ea260 R12: ffff91f7815b50c8
R13: 0000000000000cc0 R14: ffff91fafefffe30 R15: ffffb4aac0683b30
FS:  00007f033ccbe8c0(0000) GS:ffff91faeed00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f033c669379 CR3: 0000000107b1e004 CR4: 00000000003706f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ? __die+0x23/0x70
 ? page_fault_oops+0x149/0x4c0
 ? raw_spin_rq_lock_nested+0xe/0x20
 ? sched_balance_newidle+0x22b/0x3c0
 ? update_load_avg+0x78/0x770
 ? exc_page_fault+0x6f/0x150
 ? asm_exc_page_fault+0x26/0x30
 ? __pfx_pci_conf1_write+0x10/0x10
 ? strlen+0x4/0x30
 devm_kstrdup+0x25/0x70
 brcmf_of_probe+0x273/0x350 [brcmfmac]

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-21750?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-21750?

Apply the vendor's patch.

## Is CVE-2025-21750 being exploited?

There is no known exploitation of CVE-2025-21750 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-21750 and fix it if it is affected.

What it is: CVE-2025-21750 is a medium-severity vulnerability in Linux kernel, published on 27 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-21750 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-21750/ (Markdown: https://insights.sbomify.com/CVE-2025-21750/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21750
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21750
- OSV: https://osv.dev/vulnerability/CVE-2025-21750

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21750/
Summaries are generated and may contain mistakes; the official description above is the record.