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copyparty: volflag `nohtml` did not block javascript in svg files

Moderate severity GitHub Reviewed Published Mar 8, 2026 in 9001/copyparty • Updated Mar 10, 2026

Package

pip copyparty (pip)

Affected versions

<= 1.20.10

Patched versions

1.20.11

Description

Summary

The nohtml config option, intended to prevent execution of JavaScript in user-uploaded HTML files, did not apply to SVG images.

Details

A user with write-permission could upload an SVG containing embedded JavaScript, which would execute in the context of whichever user opens it.

This in itself is not a vulnerability; it is intended behavior according to the SVG spec. The vulnerability is that the nohtml volflag, when enabled, did not prevent this.

nohtml, intended for use on volumes which contains untrusted files, would correctly prevent execution of javascript in HTML files, but did not consider SVG images. This has been fixed in v1.20.11.

Impact

The malicious JavaScript could move or delete existing files on the server, or upload new files, using the account of the person who opens the SVG.

References

@9001 9001 published to 9001/copyparty Mar 8, 2026
Published to the GitHub Advisory Database Mar 10, 2026
Reviewed Mar 10, 2026
Published by the National Vulnerability Database Mar 10, 2026
Last updated Mar 10, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(9th percentile)

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

CVE-2026-30974

GHSA ID

GHSA-m6hv-x64c-27mm

Source code

Credits

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