CVE-2021-20090
Published 2021-04-29 · Updated 2026-06-17 · Source vulnreport@tenable.com
Summary
CVE-2021-20090 is a critical-severity (CVSS 9.8) vulnerability in Arcadyan Buffalo Firmware. CISA added it to the Known Exploited Vulnerabilities catalog on November 3, 2021, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by November 17, 2021. CISA does not currently list it as used in ransomware campaigns.
All 1 known-exploited Arcadyan vulnerabilities →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 vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA Known-Exploited Vulnerability
Product: Arcadyan — Buffalo Firmware
Name: Arcadyan Buffalo Firmware Path Traversal Vulnerability
Date added: 2021-11-03 · Due: 2021-11-17
Required action: Apply updates per vendor instructions.
References
- https://www.kb.cert.org/vuls/id/914124
- https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/
- https://www.tenable.com/security/research/tra-2021-13
- https://www.kb.cert.org/vuls/id/914124
- https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/
- https://www.tenable.com/security/research/tra-2021-13
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20090