CVE-2026-89009: Path Traversal (CVSS 9.1)

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.

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CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

EPSS — Exploit Prediction

0.0068

Probability of exploitation

0.51%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-36 CWE-36

References

Other References

https://docs.wavlink.xyz/ https://github.com/camdsmith/wavlink-sync_server-rce/blob/main/README.md https://www.vulncheck.com/advisories/wavlink-wn535m1-wn535m3-unauthenticated-arbitrary-file-write-via-sync-server https://github.com/camdsmith/wavlink-sync_server-rce/blob/main/README.md

Frequently Asked Questions

What is CVE-2026-89009? +

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. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-89009? +

CVE-2026-89009 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0068, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-89009? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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