What is the CVSS score of CVE-2026-21875?

CVE-2026-21875 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of PHP are affected by CVE-2026-21875?

Organizations using ClipBucket v5 face critical risk from CVE-2026-21875, a SQL injection vulnerability rated CVSS 9.8.

Is there a public PoC exploit available for CVE-2026-21875?

Yes, a public proof-of-concept exploit is available for CVE-2026-21875. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-21875?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. Validate that input sanitization is in place for all user-controlled parameters.

PHP CVE-2026-21875

CRITICAL

SQL Injection (CWE-89)

2026-01-08 security-advisories@github.com

PHP SQLi Clipbucket Oxygenz

9.8

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

PoC Detected

Jan 27, 2026 - 19:05 vuln.today

Public exploit code

CVE Published

Jan 08, 2026 - 00:16 nvd

CRITICAL 9.8

DescriptionGitHub Advisory

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.

AnalysisAI

ClipBucket v5 (5.5.2-#187 and below) has blind SQL injection in the channel comment functionality via the obj_id parameter. Unauthenticated attackers can extract the entire database. PoC available.

Technical ContextAI

The obj_id parameter in the /actions/ajax.php endpoint is used in the user_exists function without parameterization (CWE-89). The SQL injection is blind (results not directly visible) but can be exploited through time-based or boolean-based techniques for full data extraction.