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VulnerabilityPublished

CVE-2026-85035: 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 or 4.3.2 soon.

Data as of 3 Nov 2026, 13:58 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
Patch
Available – fixed in 4.5.0, 4.3.2
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 3 Nov 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 3 Nov 2026.

What to do

Upgrade zephyrproject zephyr to 4.5.0 or 4.3.2.

Affected software

ProductAffectedFixed in
zephyrprojectzephyrAffected
  • >=4.4.0 <4.5.0
Fixed in
  • 4.5.0
zephyrprojectzephyrAffected
  • >=1.14.0 <4.3.2
Fixed in
  • 4.3.2
GitHubzephyrpkg:github/zephyrOther threatsAffected
  • >=1.14.0 <4.3.2
  • >=4.4.0 <4.5.0
Fixed in
  • 4.3.2
  • 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 versions 4.3.2 and 4.5.0. Users should upgrade to these or later versions to mitigate the vulnerability. The fix restricts user-mode registration of CAN RX filters to statically defined message queues only. For supervisor-mode callers, ensure the message queue remains valid until the filter is removed.

Description

CVE-2026-85035 is a use-after-free vulnerability in the Zephyr RTOS CAN subsystem. It occurs when a user-mode thread registers a CAN RX filter with a message queue pointer that can be freed while still referenced by the kernel. Subsequent CAN frames trigger kernel heap corruption by accessing freed memory, breaking user-space isolation. The flaw affects Zephyr versions from 1.14.0 up to but excluding 4.3.2 and from 4.4.0 up to but excluding 4.5.0. The issue is fixed in versions 4.3.2 and 4.5.0 by restricting registration to statically defined queues from user mode.

References

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