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CVE-2026-89009

9.1 · CRITICAL

WAVLINK WN535M1 and WN535M3 routers running firmware prior to M35M1_V250922 contain an unauthenticated arbitrary file write vulnerability that allows remote attackers to overwrite any file on the d…

Published Sep 11, 2026CWE-36EPSS 1.01%

Overview

CVE-2026-89009 is a critical-severity vulnerability. It was published on September 11, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

WAVLINK WN535M1 and WN535M3 routers running firmware prior to M35M1_V250922 contain an unauthenticated arbitrary file write vulnerability that allows remote attackers to overwrite any file on the device by sending a crafted payload to the sync_server daemon on TCP port 13136. The daemon, which runs as root and requires no authentication, accepts a 100-byte filename field in its protocol header without path canonicalization, allowing attackers to supply an absolute path and write arbitrary content to overwrite startup scripts or credential stores to achieve persistent system compromise.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refdocs.wavlink.xyz/Security_Advisory/WAVLINK-SA-2026-091301/GitHubgithub.com/camdsmith/wavlink-sync_server-rce/blob/main/README.mdRefwww.vulncheck.com/advisories/wavlink-wn535m1-wn535m3-unauthenticated-arbitrary-file-write-via-sync-serverGitHubgithub.com/camdsmith/wavlink-sync_server-rce/blob/main/README.md

How CyberStrike helps

Frequently asked questions

What is CVE-2026-89009?

CVE-2026-89009 is a critical-severity vulnerability. It was published on September 11, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-89009?

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-89009?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-89009?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-89009 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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