Skip to content

CVE-2026-10681

Race Condition: Is CVE-2026-10681 real, exploitable, or a false positive? Here's the community verdict.

☆ Watch

signals

public sources

Exploited in wild
Not listed
CISA KEV
Public exploit
None known
Metasploit/EDB/PoC
Base severity
6.5 Medium
CVSS
Exploitation prob.
n/a
FIRST EPSS
Weakness
CWE-362 · Race Condition
CWE

Moderate signals. Triage by your actual exposure and reachability.

baseline read

auto · not a community verdict

Low signal — verdict needed

Few public signals point to active risk. Whether a scanner hit here is a true or false positive depends on your version and config — community verdicts decide.

Based on CVSS

Confirm or dispute →

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

In Zephyr's userspace dynamic-objects subsystem, thread_idx_alloc() in kernel/userspace/userspace.c allocated a new thread permission index from the global _thread_idx_map[] bitmap without holding lists_lock. On SMP systems, two user-mode threads invoking the k_object_alloc(K_OBJ_THREAD) syscall concurrently can both observe the same low free bit, perform the same non-atomic RMW to clear it, and return the identical tidx. The two newly created K_OBJ_THREAD objects are then assigned the same thread_id, so the two user threads alias a single bit position in every kernel object's perms[] bitfield: any subsequent grant of access on a kernel object to one thread is implicitly a grant to the other, defeating userspace ACL isolation. A secondary lost-update window between the unlocked &=~BIT() in alloc and the locked |= BIT() in thread_idx_free() can also leak entries from the thread-index pool. The defect is reachable from any user-mode thread via the unrestricted __syscall k_object_alloc and is gated on CONFIG_USERSPACE, CONFIG_DYNAMIC_OBJECTS, and CONFIG_SMP. The flaw was introduced when the per-thread permission index was added in 2018 and is present in every release up to and including v4.4.0. Fixed by holding lists_lock across the bitmap RMW and the permissions clear (and inlining the obj_list traversal that previously took the lock itself).

References

NVD MITRE CVE.org

Published

Embed this verdict
TruePositive verdict for CVE-2026-10681
Markdown
[![TruePositive verdict](https://www.truepositive.app/cve/CVE-2026-10681/badge.svg)](https://www.truepositive.app/cve/CVE-2026-10681)
HTML
<a href="https://www.truepositive.app/cve/CVE-2026-10681"><img src="https://www.truepositive.app/cve/CVE-2026-10681/badge.svg" alt="TruePositive verdict for CVE-2026-10681"></a>

Live badge that updates automatically as the community verdict changes.

Community ground truth

Be the first practitioner to weigh in

So far this is only TruePositive's editorial baseline from public sources. Add your real-world verdict below — it becomes the signal the next person triaging this relies on.

🥇 The first 50 practitioners to contribute earn a Founding Contributor badge.

In your experience, is this finding real and exploitable?

awaiting field verdicts
Real, but not a risk here
Not a real issue

No account needed. Anonymous verdicts post as an unverified signal. Log in to make yours verified and earn reputation.

Field notes & remediation

Verdicts are the quick signal. Notes are the evidence and fixes behind them.

No notes yet. Be the first to share what you saw, or a fix that worked.

    Add a field note or remediationoptional
    Note type

    What are you adding?

    Markdown supported · minimum 20 characters.

    Related CVEs

    Same weakness: CWE-362 · Race Condition.