CVE-2026-21663 is a reflected Cross-Site Scripting (XSS) vulnerability in the banner-acl.php script of Revive Adserver version 6. An attacker can craft a malicious URL containing an HTML payload that executes when a logged-in administrator visits it, potentially compromising session integrity and enabling unauthorized actions. The vulnerability requires user interaction (administrator clicking the link) but does not require prior authentication to trigger the malicious payload. The CVSS score is 6.1 (medium severity), reflecting the moderate impact on confidentiality and integrity without affecting availability. No known exploits are currently reported in the wild. European organizations using Revive Adserver version 6 should prioritize patching or mitigating this vulnerability to prevent targeted attacks. Countries with high digital advertising activity and significant use of Revive Adserver, such as Germany, the UK, and France, are more likely to be affected. Mitigation includes restricting administrator access to trusted networks, implementing web application firewalls with XSS protections, and educating administrators about phishing risks.
HackerOne community member Faraz Ahmed (PakCyberbot) has reported a format string injection in the Revive Adserver settings. When specific character combinations are used in a setting, the admin user console could be disabled due to a fatal PHP error.
HackerOne community member Jad Ghamloush (0xjad) has reported an authorization bypass vulnerability in the `tracker-delete.php` script of Revive Adserver. Users with permissions to delete trackers are mistakenly allowed to delete trackers owned by other accounts.
HackerOne community member Kassem S.(kassem_s94) has reported that username handling in Revive Adserver was still vulnerable to impersonation attacks after the fix for CVE-2025-52672, via several alternate techniques. Homoglyphs based impersonation has been independently reported by other HackerOne users, such as itz_hari_ and khoof.
Improper input neutralization in the stats-conversions.php script in Revive Adserver 5.5.2 and 6.0.1 and earlier versions causes potential information disclosure and session hijacking via a stored XSS attack.
Authorization bypass in Revive Adserver 5.5.2 and 6.0.1 and earlier versions causes an logged in attacker to change other users' email address and potentialy take over their accounts using the forgot password functionality.
Improper neutralization of input in Revive Adserver 5.5.2 and 6.0.1 and earlier versions causes manager accounts to be able to craft XSS attacks to their own advertiser users.
Debug information disclosure in the SQL error message to in Revive Adserver 5.5.2 and 6.0.1 and earlier versions causes non-admin users to acquire information about the software, PHP and database versions currently in use.
Improper neutralisation of format characters in the settings of Revive Adserver 5.5.2 and 6.0.1 and earlier versions causes an administrator user to disable the admin user console due to a fatal PHP error.
Insecure design policies in the user management system of Revive Adserver 5.5.2 and 6.0.1 and earlier versions causes non-admin users to have access to the contact name and email address of other users on the system.
Missing authorization check in Revive Adserver 5.5.2 and 6.0.1 and earlier versions causes users on the system to delete banners owned by other accounts
Missing JSON Content-Type header in a script in Revive Adserver 6.0.1 and 5.5.2 and earlier versions causes a stored XSS attack to be possible for a logged in manager user.
HackerOne community member Dang Hung Vi (vidang04) has reported a stored XSS vulnerability involving the navigation box at the top of advertiser-related pages, with campaign names being the vector for the stored XSS
HackerOne community member Dao Hoang Anh (yoyomiski) has reported an improper neutralization of whitespace in the username when adding new users. A username with leading or trailing whitespace could be virtually indistinguishable from its legitimate counterpart when the username is displayed in the UI, potentially leading to confusion.
HackerOne community member Dang Hung Vi (vidang04) has reported an uncontrolled resource consumption vulnerability in the “userlog-index.php”. An attacker with access to the admin interface could request an arbitrarily large number of items per page, potentially leading to a denial of service.
A reflected Cross-Site Scripting (XSS) vulnerability has been identified in Revive Adserver version 5.5.2. An attacker could trick a user with access to the user interface of a Revive Adserver instance into clicking on a specifically crafted URL and execute injected JavaScript code in the context of the victim's browser. The session cookie cannot be accessed, but a number of other operations could be performed.
The vulnerability is present in the admin-search.php file and can be exploited via the compact parameter.
SQL injection in Revive Adserver 6.0.0 causes potential disruption or information access when specifically crafted payloads are sent by logged in users
