Is CVE-2021-22873 actively exploited?

Yes. CVE-2021-22873 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2021-22873 be exploited remotely?

The attack vector of CVE-2021-22873 has not been classified yet.

What is the CVSS score of CVE-2021-22873?

CVE-2021-22873 has not received a CVSS score yet.

HOME VULNERABILITIESCVE-2021-22873

UNKNOWNCISA KEVIN THE WILD

CVE-2021-22873

Published: April 11, 2026

EPSS:46.20%probability of exploitation in 30 daysPercentile:97.6th

Official Description

Revive Adserver before 5.1.0 is vulnerable to open redirects via the `dest`, `oadest`, and/or `ct0` parameters of the lg.php and ck.php delivery scripts. Such open redirects had previously been available by design to allow third party ad servers to track such metrics when delivering ads. However, third party click tracking via redirects is not a viable option anymore, leading to such open redirect functionality being removed and reclassified as a vulnerability.

NVD Source

Technical Analysis

CVE-2021-22873 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-2021-22873 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.