---
title: "CVE-2026-89009: WAVLINK WN535M - Arbitrary File Write"
description: "WAVLINK WN535M1 and WN535M3 routers < M35M1_V250922 contain an unauthenticated arbitrary file write vulnerability caused by lack of path canonicalization in sync_server daemon on TCP port 13136, letting remote attackers overwrite files as root, exploit requires no authentication."
url: https://panop.io/threat-heartbeat/CVE-2026-89009/
---

# CVE-2026-89009 WAVLINK WN535M - Arbitrary File Write

WAVLINK WN535M1 and WN535M3 routers < M35M1\_V250922 contain an unauthenticated arbitrary file write vulnerability caused by lack of path canonicalization in sync\_server daemon on TCP port 13136, letting remote attackers overwrite files as root, exploit requires no authentication.

CVSS base score 9.1 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

1.01% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89009)

## Details

Type

Arbitrary File Write

Impact

File System Write, Privilege Escalation

CVSS vector

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

Published

11 September 2026

Updated

15 October 2026

Weakness

[CWE-36](https://cwe.mitre.org/data/definitions/36.html)

## Vendor fix

Update to firmware version M35M1\_V250922 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-89009](https://nvd.nist.gov/vuln/detail/CVE-2026-89009)
- [https://docs.wavlink.xyz/](https://docs.wavlink.xyz/)
- [https://github.com/camdsmith/wavlink-sync\_server-rce/blob/main/README.md](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://www.vulncheck.com/advisories/wavlink-wn535m1-wn535m3-unauthenticated-arbitrary-file-write-via-sync-server)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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