CVE-2026-32109

If an attacker has been given both read- and write-permissions to the server, they can upload a malicious file with the filename .prologue.html and then craft a link to potentially execute arbitrary JavaScript in the victim's context.

Note that it is intended behavior that the JavaScript would execute if the target clicks a link to the HTML file itself; "https://example.com/foo/.prologue.html". The vulnerability is that "https://example.com/foo/?b" would also evaluate the file, making the behavior unexpected.

There are existing preventative measures (strict SameSite cookies) which makes it harder to leverage this vulnerability in an attack; in order to gain control of the target's authenticated session, the link must be clicked from a page served by the server itself -- most likely by editing an existing resource, which would require additional access permissions.

Finally, for this attack to be successful, the attacker's target must click the specific crafted link given by the attacker. This vulnerability is not activated by normally browsing the web-UI on the server.

If successful, 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 link.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2026-32109 has a CVSS score of 3.7 (Low). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.20.12); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-32109? CVE-2026-32109 is a low-severity cross-site scripting (XSS) vulnerability in copyparty (pip), affecting versions < 1.20.12. It is fixed in 1.20.12. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2026-32109? CVE-2026-32109 has a CVSS score of 3.7 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of copyparty are affected by CVE-2026-32109? copyparty (pip) versions < 1.20.12 is affected.
4. Is there a fix for CVE-2026-32109? Yes. CVE-2026-32109 is fixed in 1.20.12. Upgrade to this version or later.
5. Is CVE-2026-32109 exploitable, and should I be worried? Whether CVE-2026-32109 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-32109 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-32109? Upgrade copyparty to 1.20.12 or later.