CVE-2021-20090

Name: CVE-2021-20090
Creator: NVD / NIST
Published: 2021-04-29T15:15:10.63+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10Actively ExploitedEPSS 99.98%

Last modified Jun 17, 2026

CVE-2021-20090 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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 has confirmed active exploitation in the wild. EPSS estimates a 99.98% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

99.98%

100.0th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by Nov 17, 2021.

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Buffalo	Wsr-2533dhpl2-Bk Firmware	<= 1.02
Buffalo	Wsr-2533dhp3-Bk Firmware	<= 1.24

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

Timeline

Published: Apr 29, 2021
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-20090?

How severe is CVE-2021-20090?

CVE-2021-20090 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 99.98% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2021-20090?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20090?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST