# CVE-2021-20090: Arcadyan Buffalo Firmware Path Traversal Vulnerability

> CVE-2021-20090: Arcadyan Buffalo Firmware Path Traversal Vulnerability. CVSS 9.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2021-20090
Last updated: 2025-10-21T23:25:47Z

- Published: 2021-04-29 00:00 UTC · Updated: 2025-10-21 23:25 UTC · Assigner: tenable
- CVSS: 9.8 (CVSS 3.1) · Severity: Critical · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS: 100.0%, 100th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2021-11-03, federal due date 2021-11-17, ransomware use: Unknown

## 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.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- n/a: Buffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-20090)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2021-20090)
- [https://www.kb.cert.org/vuls/id/914124](https://www.kb.cert.org/vuls/id/914124)
- [https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/](https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/)
- [https://www.tenable.com/security/research/tra-2021-13](https://www.tenable.com/security/research/tra-2021-13)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2021-20090 · Markdown: https://rewindex.com/cve/CVE-2021-20090.md · JSON: https://rewindex.com/api/v1/cves/CVE-2021-20090 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:15:20.782Z