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ZephyrOperating system · Zephyrproject

CVE-2026-10670

MEDIUM · 5.5 CVSS v3.1 Published 2026-07-14
Fix available
A fix is available. Upgrade to 4.5.0 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click 5 weeks old

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
The CONFIG_USERSPACE verification handler for the k_thread_name_copy() system call (z_vrfy_k_thread_name_copy() in kernel/thread.c) calls k_object_find() on the caller-supplied thread pointer and then dereferences the returned struct k_object without checking it for NULL. k_object_find() returns NULL whenever the supplied pointer is not a registered (static or dynamic) kernel object. The pre-fix guard tested thread == NULL instead of ko == NULL, so an unprivileged user-mode thread that invokes k_thread_name_copy() with any non-NULL but unregistered pointer (e.g. an arbitrary address) passes the NULL test, after which the verifier reads ko->type through a NULL pointer. Because the syscall verifier runs in supervisor mode, this NULL dereference is a kernel-mode fault that halts or reboots the system, allowing untrusted user code to crash the kernel across the userspace security boundary (denial of service). The marshaller passes the thread argument to the verifier without any prior K_SYSCALL_OBJ validation, so the bad pointer reaches the defect directly. The flaw affects builds with CONFIG_USERSPACE and CONFIG_THREAD_NAME enabled and has been present since the special-case lookup was introduced around v2.0.0; it is present in v4.4.0 and earlier. The fix changes the guard to check the k_object_find() return value (ko == NULL) before dereferencing it.

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 · high confidence

In Zephyr RTOS, the k_thread_name_copy() syscall verifier (z_vrfy_k_thread_name_copy()) fails to validate the return value from k_object_find() before dereferencing it. An unprivileged user-mode thread can pass any non-NULL unregistered pointer to trigger a NULL pointer dereference in kernel mode, causing kernel panic/reboot (DoS).

MitigationUpdate Zephyr to the patched version. For mitigation, verify that CONFIG_USERSPACE and CONFIG_THREAD_NAME are not both enabled in production builds unless the fix is applied.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
ZephyrOperating system
Affected:>= 2.0.0, < 4.5.0

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify CONFIG_USERSPACE is enabled
    Inspect the Zephyr build configuration (prj.conf, defconfig, or .config) for the line CONFIG_USERSPACE=y
    Affected if CONFIG_USERSPACE is set to y
  2. Verify CONFIG_THREAD_NAME is enabled
    Inspect the Zephyr build configuration for the line CONFIG_THREAD_NAME=y
    Affected if CONFIG_THREAD_NAME is set to y
  3. Confirm user mode threads are in use
    Check if the application creates user mode threads (K_USER thread options) or loads user mode modules via K_MODULE or K_OBJECT
    Affected if The system runs user-mode threads alongside the vulnerable syscall interface
  4. Check Zephyr version against fixed release
    Locate the Zephyr version in the build artifacts or SDK (typically in version.c, or the zephyr version string from 'west version' or 'git describe --tags')
    Affected if The installed Zephyr version predates the security fix for this syscall validation issue

The system is affected if CONFIG_USERSPACE and CONFIG_THREAD_NAME are both enabled in the build configuration and the Zephyr version has not yet received the k_object_find() return value validation patch.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 4.5.0 or later
Fixed in 4.5.0
Interim mitigation

Update Zephyr to the patched version. For mitigation, verify that CONFIG_USERSPACE and CONFIG_THREAD_NAME are not both enabled in production builds unless the fix is applied.

Recommended fix High confidence

Upgrade to Zephyr v4.4.1 or later (the fix was merged after v4.4.0)

  1. Apply the fix to kernel/thread.c in the z_vrfy_k_thread_name_copy() function: change the NULL check from 'if (thread == NULL)' to 'if (ko == NULL)' before dereferencing ko->type
  2. Rebuild the Zephyr image with CONFIG_USERSPACE and CONFIG_THREAD_NAME enabled
  3. Verify the fix by testing k_thread_name_copy() with an arbitrary unregistered pointer - the system call should now return an error instead of crashing
  4. Alternatively, upgrade to a release version that includes this fix (see upgrade_path)

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

Fix this in Zephyr Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,210
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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-2026-10670 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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