CVE-2026-21875
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedClipBucket 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceClipBucket v5 versions 5.5.2-#187 and below contain a Blind SQL Injection vulnerability in the /actions/ajax.php endpoint. The obj_id parameter from POST requests is passed unsanitized to the user_exists function in upload/includes/classes/user.class.php, then to the count function in upload/includes/classes/db.class.php where it is directly concatenated into SQL queries. Attackers can inject payloads like 1' or 1=1-- - to extract data or cause denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 5.3, < 5.5.2-191CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Verify ClipBucket is installedCheck for the presence of ClipBucket directories, typically in the web root. Look for directories named 'upload', 'actions', 'includes', or files like 'index.php', 'install.php'.Affected if ClipBucket is not found on the system - not applicable
-
Determine installed ClipBucket versionLocate the version file or configuration. Common locations include: a version.php file in the root or includes directory, a version constant in config.php, or check the admin dashboard for version information. Compare your found version against the affected range: >=5.3 and <5.5.2-191.Affected if Installed version falls within >=5.3 and <5.5.2-191 - the system may be vulnerable
-
Check if vulnerable ajax.php endpoint existsVerify the existence of the file 'actions/ajax.php' in the ClipBucket installation directory. This is the endpoint where the obj_id parameter is processed.Affected if The file actions/ajax.php exists and is accessible - vulnerability may be present if version is affected
-
Verify vulnerable code path in user.class.phpExamine the file 'upload/includes/classes/user.class.php' and look for the user_exists function. Check if the obj_id parameter is passed directly to database queries without sanitization or parameterized queries.Affected if The user_exists function accepts obj_id and passes it unsanitized to database operations - the SQL injection flaw is present
A system is affected if it runs ClipBucket version 5.3 through 5.5.2-#187 (below 5.5.2-191) with the vulnerable ajax.php endpoint and unsanitized obj_id parameter handling present in the code.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped5.5.2-191
Implement parameterized queries/prepared statements for all database operations, particularly in user.class.php and db.class.php. Additionally, add strict input validation and type checking for the obj_id parameter before any database interaction.
- This vulnerability currently has no available patch or fix according to the official description.
- Monitor the ClipBucket GitHub repository (github.com) for future security updates.
- Consider implementing Web Application Firewall (WAF) rules to detect and block SQL injection patterns in the obj_id parameter.
- Implement input validation and parameterized queries at the application level as a temporary mitigation.
- Restrict access to the /actions/ajax.php endpoint if possible until a fix is released.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,960.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-21875 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-21875 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data