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CVE-2026-12365— Use-after-free in Zephyr delayable work-queue cancellation under SMP timing race

Quick assessment

Affected
zephyrproject zephyr
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Zephyr Project zephyr是Zephyr Project组织开源的一个面向物联网设备的实时操作系统。 Zephyr Project zephyr 2.6.0版本至4.5.0之前版本存在资源管理错误漏洞，该漏洞源于kernel/work.c中处理延迟工作超时时，并发取消未等待处理完成，导致释放后重用，可能造成内核内存损坏或崩溃（拒绝服务）。

CVSS 5.8 · Medium EPSS 0.10% · P1

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 1

VendorProduct Version RangeStatus
zephyrproject zephyr 2.6.0< 4.5.0 affected
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I. Basic Information for CVE-2026-12365

Vulnerability Information
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Vulnerability Title
Use-after-free in Zephyr delayable work-queue cancellation under SMP timing race
Source: CVE Program / CVE List V5
Vulnerability Description
A use-after-free exists in the Zephyr second-generation work queue (kernel/work.c) in the handling of delayable work timeouts. When a delayable work item's timeout has been dequeued and its handler work_timeout() is in flight (blocked acquiring the work-queue spinlock), a concurrent cancellation does not wait for that handler to finish. In unschedule_locked() the pre-fix code called z_abort_timeout(), which for an already-announcing record returns -EINVAL without removing it; cancel_async_locked() then observes the work as idle, so even k_work_cancel_delayable_sync() and k_work_flush_delayable() return without blocking on the in-flight handler. Because those are the APIs the kernel header documents as the safe way to cancel before freeing a k_work_delayable, a caller that frees the object immediately after a successful sync cancel can race the still-pending handler. work_timeout() subsequently dereferences the freed record: it reads to->dticks via z_is_timeout_handler_canceled() and, if the freed slot has been reused so the bail check fails, performs a read-modify-write of wp->flags (K_WORK_DELAYED_BIT) and submits work against a stale dw->queue pointer — a use-after-free read and write. The k_work API is kernel-mode only (no __syscall entry point), so this is a kernel-internal concurrency defect rather than a userspace privilege escalation. Triggering it requires an SMP build and a subsystem that schedules and then frees (or reschedules) a delayable work item in the narrow window while its timeout is announcing; an attacker able to influence the timing of such teardown (for example via connection churn driving subsystem timers) has a plausible but probabilistic path. The impact is kernel memory corruption or crash (denial of service). The fix makes unschedule_locked() wait, by spinning on z_try_abort_timeout() returning -EAGAIN while releasing and re-acquiring the work spinlock, until any in-flight handler completes before returning, and switches work_timeout() to atomic K_WORK_DELAYED_BIT ownership. This closes both the free-then-handler use-after-free and the related reschedule early-fire race.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
释放后使用
Source: CVE Program / CVE List V5
Vulnerability Title
Zephyr Project zephyr 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Zephyr Project zephyr是Zephyr Project组织开源的一个面向物联网设备的实时操作系统。 Zephyr Project zephyr 2.6.0版本至4.5.0之前版本存在资源管理错误漏洞，该漏洞源于kernel/work.c中处理延迟工作超时时，并发取消未等待处理完成，导致释放后重用，可能造成内核内存损坏或崩溃（拒绝服务）。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
zephyrproject zephyr 2.6.0 ~ 4.5.0 -

II. Public POCs for CVE-2026-12365

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III. Intelligence Information for CVE-2026-12365

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Patches & Fixes for CVE-2026-12365 (1)

Vendor Advisories for CVE-2026-12365 (1)

Same Patch Batch · zephyrproject · 2026-08-14 · 4 CVEs total

CVE-2026-12366 8.8 HIGH Use-after-free freeing an armed dynamically-allocated k_timer in Zephyr userspace object d
CVE-2026-12364 8.4 HIGH Missing user-space pointer validation in logging syscall z_log_msg_static_create allows ke
CVE-2026-12363 4.2 MEDIUM Out-of-bounds write in LoRaWAN fragmented transport from a fragment index of 0

IV. Related Vulnerabilities

Same product: zephyr
Same vendor: zephyrproject
Same weakness: CWE-416

V. Comments for CVE-2026-12365

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