CVE-2026-89009
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.
EPSS exploit prediction
EPSS: 0.010 (62.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 62.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000
Weakness classification (CWE)
References
- github.com/camdsmith/wavlink-sync_server-rce/blob/main/README.md (technical-description, exploit)
- docs.wavlink.xyz/ (product, patch)
- www.vulncheck.com/advisories/wavlink-wn535m1-wn535m3-unauthenticated-arbitrary-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-89009?
- CVE-2026-89009 is a critical-severity vulnerability, classified under Absolute Path Traversal. CVSS score: 9.1/10. Published 2026-09-11.
- How severe is CVE-2026-89009?
- Critical severity. CVSS v3 base score is 9.1 out of 10.