pyLoad vulnerable to XSS through insecure CAPTCHA

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2025-53890: 1.30% estimated exploitation activity in the next 30 days; percentile 70.43 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows unauthenticated remote attackers to execute arbitrary code in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system rce. Details The vulnerable code resides in The onCaptchaResult() function directly passes CAPTCHA results (sent from the user) into eval() No sanitization or validation is performed on this input A malicious CAPTCHA result can include JavaScript such as fetch() or childprocess.exec() in environments using NodeJS Attackers can fully hijack sessions and pivot to remote code execution on the server if the environment allows it Reproduction Methods 1. Official Source Installation: 2. Virtual Environment: CAPTCHA Endpoint Verification Technical Clarification: 1. The vulnerable endpoint is actually: 2. Complete PoC Request: 3. Curl Command…

Published by the source

15 Jul 2025, 15:38 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:32 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-8w3f-4r8f-pf53

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-8w3f-4r8f-pf53

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# Patch Next advisory brief: CVE-2025-53890

Advisory: pyLoad vulnerable to XSS through insecure CAPTCHA
IDs: CVE-2025-53890, GHSA-8w3f-4r8f-pf53
Record: https://patchnext.com/advisories/cve-2025-53890 (revision 2, source checked 26 Oct 2026, 13:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pyload-ng 0.20. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pyload-ng: affected < 0.20; fixed in 0.20

## Suggested inspection (read-only)
- `python -m pip show pyload-ng`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pyload-ng.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-8w3f-4r8f-pf53 (OSV record GHSA-8w3f-4r8f-pf53 lists affected ranges: PyPI pyload-ng >=0 <0.20 (fixed))
- Verified: https://github.com/advisories/GHSA-8w3f-4r8f-pf53 (GitHub-reviewed advisory GHSA-8w3f-4r8f-pf53 lists affected ranges: PyPI pyload-ng >=0 <0.20)

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