# CVE-2026-12233: Uninitialized mutex in TLS trusted-credential backend causes kernel NULL-deref DoS under contention

> Concurrent TLS handshakes trigger a kernel NULL dereference and panic in Zephyr RTOS when using the PSA Protected Storage credential backend.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Aug 2026
- **Updated:** 13 Aug 2026
- **Also known as:** GHSA-57c4-xcq2-fqj7

## What is CVE-2026-12233?

CVE-2026-12233 is a medium-severity vulnerability in zephyrproject zephyr, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The PSA Protected Storage credential backend (subsys/net/lib/tls_credentials/tls_credentials_trusted.c) declared its credential-store mutex as a plain zero-filled static struct k_mutex credential_lock; and never called k_mutex_init() on it. A statically zero-filled k_mutex has an uninitialized wait queue (its dlist head/tail are NULL instead of the self-referential sentinels that k_mutex_init/K_MUTEX_DEFINE install). The uncontended lock path does not touch the wait queue, so the defect is latent and serialized use behaves correctly.

When two execution contexts contend on the lock, k_mutex_lock() pends the blocking thread on the wait queue via z_pend_curr(), which calls sys_dlist_append() on the zeroed list and dereferences a NULL tail pointer (tail->next = node), faulting the kernel. The lock is held during TLS handshake credential loading and by all credential add/get/delete operations, so a deployment performing concurrent TLS handshakes (for example a server handling multiple simultaneous connections from a remote peer) or a credential-management operation concurrent with a handshake can trigger the dereference.

The impact is a denial of service: a deterministic kernel panic / device reset on the first contention. There is no memory corruption beyond the NULL dereference and no confidentiality or integrity impact; mutual exclusion on the fast path remains correct. Exposure is limited to builds with CONFIG_TLS_CREDENTIALS_BACKEND_PROTECTED_STORAGE enabled (PSA Protected Storage / TF-M platforms); the default volatile RAM backend initializes its lock correctly and is unaffected.

The fix initializes the mutex statically with K_MUTEX_DEFINE(credential_lock), providing a valid wait queue so the contended path no longer touches a NULL list.

Weakness: CWE-665 (Improper Initialization)

## Which versions are affected by CVE-2026-12233?


## How do I fix CVE-2026-12233?

No fix has been published for CVE-2026-12233 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-12233 being exploited?

There is no known exploitation of CVE-2026-12233 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-12233 and fix it if it is affected.

What it is: CVE-2026-12233 is a medium-severity vulnerability in zephyrproject zephyr, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-12233 in the wild and no public exploit code.

Affected product: zephyrproject zephyr. 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-2026-12233/ (Markdown: https://insights.sbomify.com/CVE-2026-12233/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-12233
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12233
- OSV: https://osv.dev/vulnerability/CVE-2026-12233

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-12233/
Summaries are generated and may contain mistakes; the official description above is the record.