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CVE-2026-21664

6.1 · MEDIUM

HackerOne community member Huynh Pham Thanh Luc (nigh7c0r3) has reported a reflected XSS vulnerability in the afr.php delivery script of Revive Adserver.

Published Jan 20, 2026CWE-79EPSS 0.20%

Overview

CVE-2026-21664 is a medium-severity vulnerability. It was published on January 20, 2026 and has a CVSS 3.0 base score of 6.1 (MEDIUM).

This vulnerability has a CVSS 3.0 base score of 6.1, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

HackerOne community member Huynh Pham Thanh Luc (nigh7c0r3) has reported a reflected XSS vulnerability in the afr.php delivery script of Revive Adserver. An attacker can craft a specific URL that includes an HTML payload in a parameter. If a logged in administrator visits the URL, the HTML is sent to the browser and malicious scripts would be executed.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refhackerone.com/reports/3468169

How CyberStrike helps

Frequently asked questions

What is CVE-2026-21664?

CVE-2026-21664 is a medium-severity vulnerability. It was published on January 20, 2026 and has a CVSS 3.0 base score of 6.1 (MEDIUM).

How severe is CVE-2026-21664?

This vulnerability has a CVSS 3.0 base score of 6.1, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-21664?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-21664?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-21664 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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