Which products and versions are affected by CVE-2021-22873?

Affected: Revive Adserver (Revive-Adserver); https://github.com/revive-adserver/revive-adserver versions >= Fixed in 5.1.0. The full list is in the CVE brief.

Is CVE-2021-22873 being exploited in the wild?

It is exploited in the wild, listed in Industry KEV feed since Nov 20, 2024.

Is CVE-2021-22873 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2021-22873?

No public exploit code is known.

Is there a fix for CVE-2021-22873?

Fixed versions are available, including Revive Adserver 5.1.0.

How urgently should CVE-2021-22873 be patched?

Brandefense priority: patch immediately, because it is listed as exploited in the wild.

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Vulnerability Intelligence

CVE-2021-22873

MediumExploited

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.

Published Jan 26, 2021 · Updated Jul 9, 2026

Key Facts

Patch immediately

CVE-2021-22873 is a medium-severity vulnerability (CVSS 6.1 v3.1) affecting Revive Adserver (Revive-Adserver), https://github.com/revive-adserver/revive-adserver.
It is exploited in the wild, listed in Industry KEV feed since Nov 20, 2024. No public exploit code is known.
EPSS estimates a 70% probability of exploitation in the next 30 days.
Fixed versions are available, including Revive Adserver 5.1.0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

CVSS v3.1

6.1

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

EPSS (30-day exploit likelihood)

70%

Higher than 99.3% of all scored CVEs

Exploited in the wild

Yes

1 catalog listing

Public exploit code

None known

Get the full CVE-2021-22873 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

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.

Known-Exploited Catalog Listings

Catalog	Added	Remediation due	Ransomware use
Industry KEV feed	Nov 20, 2024	n/a	Not reported

Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Affected Products

2 affected entries in total

Product	Affected versions	Fixed in
Revive AdserverRevive-Adserver	See advisory	5.1.0
https://github.com/revive-adserver/revive-adserver	>= Fixed in 5.1.0	n/a

Patched Releases

Revive Adserver

5.1.0

Timeline

Publicly disclosed
Jan 26, 2021
Added to Industry KEV feed
Nov 20, 2024
Last updated
Jul 9, 2026

Weakness Type

CWE-601 URL Redirection to Untrusted Site ('Open Redirect')

References

1 more references in the full CVE brief

FAQ

Common Questions.

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.
Affected: Revive Adserver (Revive-Adserver); https://github.com/revive-adserver/revive-adserver versions >= Fixed in 5.1.0. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed since Nov 20, 2024.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Revive Adserver 5.1.0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

Is CVE-2021-22873 Running On Your Attack Surface?

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