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VulnerabilityPublished Updated

CVE-2026-12366: zephyrproject zephyr · Use After Free

Affects zephyrproject zephyrSource CVE Database V5

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Not known to be exploited · CVSS 8.8 High : upgrade to 4.5.0 soon.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (zephyr)CVSS 3.18.8
EPSS
0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.5.0
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade zephyrproject zephyr to 4.5.0.

Affected software

ProductAffectedFixed in
zephyrprojectzephyrAffected
  • >=1.12.0 <4.5.0
Fixed in
  • 4.5.0
GitHubzephyrpkg:github/zephyrOther threatsAffected
  • >=1.12.0 <4.5.0
Fixed in
  • 4.5.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in Zephyr version 4.5.0 that properly cleans up timer objects before freeing their memory. Users should upgrade to version 4.5.0 or later to remediate this vulnerability. No other mitigations are indicated by the vendor advisory.

Description

CVE-2026-12366 is a use-after-free vulnerability in the Zephyr RTOS kernel's dynamic kernel-object disposal path affecting versions from 1.12.0 up to but not including 4.5.0. The flaw occurs because the cleanup code did not handle timer objects properly, leading to a dangling pointer in the global timeout queue after the timer's memory is freed. When the timer expires, the kernel dereferences freed memory in interrupt context, causing memory corruption. This vulnerability can be triggered by an unprivileged user thread and can lead to privilege escalation via sandbox escape. The issue is fixed in Zephyr version 4.5.0 by adding proper cleanup for timer objects before freeing their memory.

References

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