CVE-2022-34747 — A format string vulnerability in Zyxel NAS326 firmware versions prior to V5

A format string vulnerability in Zyxel NAS326 firmware versions prior to V5.21(AAZF.12)C0 could allow an attacker to achieve unauthorized remote code execution via a crafted UDP packet.

01What is this vulnerability?

A format string vulnerability in Zyxel NAS326 firmware versions prior to V5.21(AAZF.12)C0 could allow an attacker to achieve unauthorized remote code execution via a crafted UDP packet.

02Affected products

Vendor	Product	Versions
Zyxel	Zyxel NAS326 firmware	< V5.21(AAZF.12)C0

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2022-09-06T01:20:10.000Z
• Last modified: 2024-08-03T09:22:09.239Z

09References

• www.zyxel.com — https://www.zyxel.com/support/Zyxel-security-advisory-for-format-string-vulnerab…