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MEDIUM severity

CVE-2023-6551 — class.upload.php

MEDIUMFix: verot/class.upload.php@befbccc

CVE-2023-6551 is a medium-severity (CVSS 6.5) Unrestricted File Upload vulnerability in verot/class.upload.php. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

class.upload.php allows cross-site scripting attacks via uploaded files

Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2023-6551.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs38th percentile — riskier than 38% of all scored CVEsHighest risk
0.00%0.31%0.62%0.94%0.1%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐘verot/class.upload.php

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🐘Packagistverot/class.upload.phpall versionsNo fix

Affected Products

1 product · 1 configurations
Application
class.upload.phpverot
all

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for verot/class.upload.php, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    The records we use list no patched version of verot/class.upload.php for CVE-2023-6551. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2023-6551: class.upload.php XSS (Medium 6.5)