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

No. CVE-2021-22873 is not currently on the CISA Known Exploited Vulnerabilities list.

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

CVE-2021-22873 has a CVSS v3 base score of 6.1 (MEDIUM).

What is the EPSS score for CVE-2021-22873?

CVE-2021-22873 has an EPSS score of 66.14% (99th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-22873?

Upgrade revive adserver to 5.1.0 or later.

CVE & CISA-KEV Catalog

CVE-2021-22873

MEDIUMEPSS 99th pctl

6.1

CVSS v3

NVD

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.

CWE-601Open Redirect

How to fix

Remediation Available

revive adserverNVD

Affected:< 5.1.0Fixed in:5.1.0CVE-2021-22873derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

66.14%probability of exploitation in 30 days

99thpercentile

Very high risk: more likely to be exploited than 99% of all known CVEs.

References

Exploit1

hackerone.com

Vendor Advisory1

revive-adserver.com

Third-Party Advisory3

Related Vulnerabilities

Other CWE-601 (Open Redirect) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-4123	High	7.6	98%	-	Fix
CVE-2018-11784	Medium	4.3	94%	-	Fix
CVE-2021-22881	Medium	6.1	87%	-	Fix
CVE-2022-45402	Medium	6.1	82%	-	Fix
CVE-2017-1000117	High	8.8	78%	-	Fix
CVE-2019-10098	Medium	6.1	74%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.