CVE-2026-30974 Copyparty volflag `nohtml` did not block javascript in svg files

What is CVE-2026-30974?

CVE-2026-30974 is a medium-severity cross-site scripting vulnerability in 9001 copyparty, published on 10 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

Copyparty is a portable file server. Prior to v1.20.11., the nohtml config option, intended to prevent execution of JavaScript in user-uploaded HTML files, did not apply to SVG images. A user with write-permission could upload an SVG containing embedded JavaScript, which would execute in the context of whichever user opens it. This has been fixed in v1.20.11.

Weakness: CWE-79

Which versions are affected by CVE-2026-30974?

3 open source packages ship an affected version, including copyparty. It affects 1 product.

Products include 9001 Copyparty.

How do I fix CVE-2026-30974?

Upgrade copyparty to 1.20.11 or later.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-30974 being exploited?

There is no known exploitation of CVE-2026-30974 in the wild and no public exploit code.

Other vulnerabilities in 9001 copyparty

• CVE-2023-41471 Cross-site scripting in n/a High 7.8
• CVE-2025-54796 Copyparty is vulnerable to Regex Denial of Service (ReDoS) attacks through "Recent Uploads" page High 7.5
• CVE-2023-37474 Path traversal in copyparty High 7.5
• CVE-2025-54589 copyparty Reflected XSS via Filter Parameter Medium 6.3
• CVE-2023-38501 copyparty vulnerable to reflected cross-site scripting via k304 parameter Medium 6.3

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-m6hv-x64c-27mm, PYSEC-2026-2137.