CVE-2026-21875

CriticalPublic PoC

Published: 08 January 2026

Published

08 January 2026

Modified

27 January 2026

KEV Added

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Patch

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CVSS Score 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Score 0.0006 18.7th percentile

Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-21875 is a critical-severity SQL Injection (CWE-89) vulnerability in Oxygenz Clipbucket. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 18.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-10 (Information Input Validation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190). What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match

prevent

Directly mitigates blind SQL injection by enforcing validation of the unsanitized obj_id parameter before its use in database queries.

SI-2 Flaw Remediation good match

preventrecover

Addresses the vulnerability by requiring identification, testing, and application of fixes or patches for the SQL injection flaw in ClipBucket.

RA-5 Vulnerability Monitoring and Scanning good match

detect

Enables detection of the blind SQL injection vulnerability through regular vulnerability scanning of the affected web application endpoints.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

Why these techniques?

Direct remote exploitation of unauthenticated blind SQL injection in public-facing web app endpoint (/actions/ajax.php).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

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.

Deeper analysisAI

CVE-2026-21875 is a Blind SQL Injection vulnerability (CWE-89) in ClipBucket v5, an open source video sharing platform. It affects versions 5.5.2-#187 and below. The issue arises in the add comment section within a channel, where a POST request to the /actions/ajax.php endpoint passes the obj_id parameter directly to the user_exists function in upload/includes/classes/user.class.php. This parameter is then used unsanitized in the count function within upload/includes/classes/db.class.php, allowing injection via payloads like 1' or 1=1-- -.

An unauthenticated attacker (PR:N) with network access (AV:N) can exploit this vulnerability with low complexity (AC:L) and no user interaction (UI:N). By submitting a crafted obj_id in the POST request, they can trigger blind SQL injection, achieving high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H), as rated 9.8 by CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

The GitHub security advisory GHSA-crpv-fmc4-j392 states that no fix is available at the time of publication on 2026-01-08. Administrators should restrict access to affected endpoints, validate inputs, or upgrade upon patch release.