PatchTheCVECVE-2023-6551: As a simple library, class.upload.php does not perform an in-depth check on uploaded files, allowing a stored
CVE-2023-6551 is a medium-severity flaw (CVSS 5.4) affecting class.upload.php. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
As a simple library, class.upload.php does not perform an in-depth check on uploaded files, allowing a stored XSS vulnerability when the default configuration is used. Developers must be aware of that fact and use extension whitelisting accompanied by forcing the server to always provide content-type based on the file extension. The README has been updated to include these guidelines.
Why this priority
- No elevated risk signals yet
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 5.4 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | Required |
| EPSS exploit chance | 0.4% (top 62%) |
| CISA exploited list | No |
| Weakness | CWE-434 |
| Published | 2024-01-04 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2023-6551?
class.upload.php: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2023-6551 being exploited?
CVE-2023-6551 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2023-6551 affect?
CVE-2023-6551 affects class.upload.php. Severity is medium (CVSS 5.4). As a simple library, class.upload.php does not perform an in-depth check on uploaded files, allowing a stored XSS vulnerability when the default configuration is used. Developers must be aware of that fact and use extension whitelisting
How urgent is CVE-2023-6551?
Priority 28/100. No elevated risk signals yet.