Is CVE-2021-20091 actively exploited?

Yes. CVE-2021-20091 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2021-20091 be exploited remotely?

The attack vector of CVE-2021-20091 has not been classified yet.

What is the CVSS score of CVE-2021-20091?

CVE-2021-20091 has not received a CVSS score yet.

HOME VULNERABILITIESCVE-2021-20091

UNKNOWNCISA KEVIN THE WILD

CVE-2021-20091

Published: April 11, 2026

EPSS:86.76%probability of exploitation in 30 daysPercentile:99.4th

Official Description

The web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 do not properly sanitize user input. An authenticated remote attacker could leverage this vulnerability to alter device configuration, potentially gaining remote code execution.

NVD Source

Technical Analysis

CVE-2021-20091 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CISA has added CVE-2021-20091 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.