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Fencer Vulns
medium 5.4

CVE-2023-6551 json

Stored XSS in class.upload.php

published 2024-01-04 2 y ago modified 2026-06-17 4 mo ago also GHSA-v6f4-jwv9-682w , EUVD-2024-0433

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

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.

Patch / fix

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
packagist verot/class.upload.php
<=2.1.6
 no fix listed

Affected products

  • class.upload.php class.upload.php

Classification

Weakness
  • CWE-434 Unrestricted Upload of File with Dangerous Type
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.