MacWarrior clipbucket-v5 up to 5.5.2-#187 POST Request /actions/ajax.php user_exists ID sql injection

Summaryinfo

A vulnerability marked as critical has been reported in MacWarrior clipbucket-v5 up to 5.5.2-#187. Affected is the function user_exists of the file /actions/ajax.php of the component POST Request Handler. Performing a manipulation of the argument ID results in sql injection. This vulnerability is reported as CVE-2026-21875. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as critical, was found in MacWarrior clipbucket-v5 up to 5.5.2-#187. This affects the function user_exists of the file /actions/ajax.php of the component POST Request Handler. The manipulation of the argument id with an unknown input leads to a sql injection vulnerability. CWE is classifying the issue as CWE-89. The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

ClipBucket v5 is an open source video sharing platform. Versions 5.5.2-#187 and below allow an attacker to perform Blind SQL Injection through the add comment section within a channel. When adding a comment within a channel, there is a POST request to the /actions/ajax.php endpoint. The obj_id parameter within the POST request to /actions/ajax.php is then used within the user_exists function of the upload/includes/classes/user.class. php file as the $id parameter. It is then used within the count function of the upload/includes/classes/db.class. php file. The $id parameter is concatenated into the query without validation or sanitization, and a user-supplied input like 1' or 1=1-- - can be used to trigger the injection. This issue does not have a fix at the time of publication.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-21875 since 01/05/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 01/08/2026). The attack technique deployed by this issue is T1505 according to MITRE ATT&CK.

By approaching the search of inurl:actions/ajax.php it is possible to find vulnerable targets with Google Hacking.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• MacWarrior

Name

• clipbucket-v5

Version

• 5.5.2-#187

Website

• Product: https://github.com/MacWarrior/clipbucket-v5/

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