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CVE-2025-9558VulnerabilityPublished Updated

CVE-2025-9558: zephyrproject-rtos Zephyr · Classic Buffer Overflow

Affects zephyrproject-rtos ZephyrSource CVE Database V5

0

Not known to be exploited · CVSS 7.6 High : upgrade to 4.2.2 soon.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score
7.6High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.2.2
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 26 Nov 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 2026-10-26.

What to do

Upgrade zephyrproject-rtos Zephyr to 4.2.2.

Affected software

ProductAffectedFixed in
zephyrproject-rtosZephyrAffected
  • <4.2.2
Fixed in
  • 4.2.2
GitHubzephyrproject-rtos/zephyrpkg:github/zephyrproject-rtos/zephyrOther threatsAffected
  • *
Fixed in–
GitHubZephyrpkg:github/ZephyrOther threatsAffected
  • <4.2.2
Fixed in
  • 4.2.2

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

AI-suggested

European organizations should implement a multi-layered mitigation strategy. First, monitor Zephyr project communications and apply official patches promptly once released to address CVE-2025-9558. If you cannot patch yet, consider deploying network-level controls such as segmentation and firewall rules to restrict access to devices running Zephyr, especially blocking untrusted or external network traffic to vulnerable services. Conduct thorough code audits and static analysis on custom Zephyr-based firmware to identify and remediate unsafe buffer handling. Employ runtime protections like stack canaries, address space layout randomization (ASLR), and memory protection units (MPUs) where supported by hardware to reduce exploitation success. Implement strict input validation and size checks in any custom code interfacing with the affected functions. Regularly perform vulnerability scanning and penetration testing focused on embedded devices to detect exploitation attempts. Finally, maintain an inventory of all Zephyr-based devices in the environment to prioritize risk management and incident response planning.

Description

There is a potential OOB Write vulnerability in the gen_prov_start function in pb_adv.c. The full length of the received data is copied into the link.rx.buf receiver buffer without any validation on the data size.

References

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