CVE-2021-20090
Arcadyan Buffalo Firmware Path Traversal Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2021). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote attackers to bypass authentication.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 99.98% probability · 100th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 3 November 2021 · due 17 November 2021
- Weakness
- CWE-22
- Affected
- buffalo/wsr-2533dhpl2-bk firmware · buffalo/wsr-2533dhp3-bk firmware
- Source
- vulnreport@tenable.com
EPSS 100.0% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-20090
References
- https://www.kb.cert.org/vuls/id/914124Third Party Advisory, US Government Resource
- https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/Exploit, Third Party Advisory
- https://www.tenable.com/security/research/tra-2021-13Exploit, Third Party Advisory
- https://www.kb.cert.org/vuls/id/914124Third Party Advisory, US Government Resource
- https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/Exploit, Third Party Advisory
- https://www.tenable.com/security/research/tra-2021-13Exploit, Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20090US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.