CVE-2026-32109: Copyparty Copyparty Has Unexpected JavaScript Execution Vulnerability

LOW
Advisory Identifier: GHSA-rcp6-88mm-9vgf
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CVSS 3.7
CWE-79
Published
Advisory Summary

CVE-2026-32109 is a LOW (CVSS 3.7) copyparty has unexpected javascript execution vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Copyparty libraries in the PyPI ecosystem. The issue involves copyparty has unexpected javascript execution via crafted url to folder with `.prologue.html`. Remediation is available by upgrading affected packages to version 1.20.12.

CVE-2026-32109 at a Glance

CVE Identifier CVE-2026-32109
GHSA Identifier GHSA-rcp6-88mm-9vgf
Severity LOW
CVSS v3.1 Base Score 3.7
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Copyparty
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 3.7

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-32109

To remediate this vulnerability, upgrade all affected Copyparty dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

copyparty fixed: 1.20.12 
pip install copyparty>=1.20.12
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show copyparty

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-32109, inspect your installed packages using pip:

pip show copyparty

Analyze the terminal output to locate any version of Copyparty in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.20.12), your application is affected.

Note: The pip show copyparty command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where 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. In Copyparty, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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. ## Impact 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.

CVE-2026-32109 Affected Copyparty Versions

1 component(s)
Fixed Versions:
1.20.12
Product / Package Ecosystem Affected Versions Fixed Version
copyparty
pypi/copyparty
PyPI
< 1.20.12
1.20.12

References

GitHub Advisory / Wiki ADVISORY
https://github.com/9001/copyparty/security/advisories/GHSA-rcp6-88mm-9vgf
NVD — CVE-2026-32109 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-32109
Copyparty Source Repository REPOSITORY
https://github.com/9001/copyparty
Copyparty Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/copyparty/PYSEC-2026-32.yaml

Frequently Asked Questions

What is CVE-2026-32109?
CVE-2026-32109 is a security vulnerability in Copyparty involving Copyparty has unexpected JavaScript execution via crafted URL to folder with `.prologue.html` under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Copyparty versions are affected?
Affected versions include releases prior to 1.20.12 across affected packages: copyparty.
What version fixes CVE-2026-32109?
Upgrading to 1.20.12 (or the latest patched release for your respective branch) resolves the vulnerability.
Is copyparty affected?
Yes, copyparty is affected in releases prior to 1.20.12. Upgrade your dependency to 1.20.12 or later.
What is the CVSS score of CVE-2026-32109?
CVE-2026-32109 has a CVSS v3.1 base score of 3.7 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-32109?
CVE-2026-32109 is classified under CWE-79: 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.).
How can I check PyPI dependencies for CVE-2026-32109?
Run the dependency tree command: 'pip show copyparty'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rcp6-88mm-9vgf",
  "modified" : "2026-06-05T17:51:18Z",
  "published" : "2026-03-12T14:22:53Z",
  "aliases" : [ "CVE-2026-32109" ],
  "summary" : "Copyparty has unexpected JavaScript execution via crafted URL to folder with `.prologue.html`",
  "details" : "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.\n\nNote 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.\n\nThere 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.\n\nFinally, 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.\n\n## Impact\n\nIf 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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "copyparty"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.20.12"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/9001/copyparty/security/advisories/GHSA-rcp6-88mm-9vgf"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-32109"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/9001/copyparty"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/copyparty/PYSEC-2026-32.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-12T14:22:53Z",
    "nvd_published_at" : "2026-03-11T21:16:16Z"
  }
}