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VulnerabilityPublished Updated

CVE-2026-5590: zephyrproject-rtos Zephyr · NULL Pointer Dereference

Affects zephyrproject-rtos ZephyrSource CVE Database V5

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Not known to be exploited · CVSS 6.4 Medium : upgrade to 4.3.1 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
6.4Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.3.1
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 5 Apr 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 29 Oct 2026.

What to do

Upgrade zephyrproject-rtos Zephyr to 4.3.1.

Affected software

ProductAffectedFixed in
zephyrproject-rtosZephyrAffected
  • <4.3.1
Fixed in
  • 4.3.1
GitHubzephyrproject-rtos/zephyrpkg:github/zephyrproject-rtos/zephyrOther threatsAffected
  • *
Fixed in–
GitHubZephyrpkg:github/ZephyrOther threatsAffected
  • <4.3.1
Fixed in
  • 4.3.1

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

AI-suggested

No vendor advisory or patch links are currently provided, so no specific mitigation steps can be recommended beyond awaiting an official fix.

Description

A race condition during TCP connection teardown can cause tcp_recv() to operate on a connection that has already been released. If tcp_conn_search() returns NULL while processing a SYN packet, a NULL pointer derived from stale context data is passed to tcp_backlog_is_full() and dereferenced without validation, leading to a crash.

References

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