Pterodactyl Panel vulnerable to authentication bypass due to improper user-provided security token verification

Exploitation

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

CVSS

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

EPSS

• CVE-2021-41129: 1.75% estimated exploitation activity in the next 30 days; percentile 77.92 (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.

A malicious user can modify the contents of a confirmationtoken input during the two-factor authentication process to reference a cache value not associated with the login attempt. In rare cases this can allow a malicious actor to authenticate as a random user in the Panel. The malicious user must target an account with two-factor authentication enabled, and then must provide a correct two-factor authentication token before being authenticated as that user. Impact Due to a validation flaw in the logic handling user authentication during the two-factor authentication process a malicious user can trick the system into loading credentials for an arbitrary user by modifying the token sent to the server. This authentication flaw is present in the LoginCheckpointController@invoke method which handles two-factor authentication for a user. This controller looks for a request input parameter called confirmationtoken which is expected to be a 64 character random alpha-numeric string that…

Published by the source

4 Oct 2021, 20:14 UTC

Last modified by the source

27 Jan 2023, 05:00 UTC

Source last checked

26 Oct 2026, 13:59 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5vfx-8w6m-h3v4

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# Patch Next advisory brief: CVE-2021-41129

Advisory: Pterodactyl Panel vulnerable to authentication bypass due to improper user-provided security token verification
IDs: CVE-2021-41129, GHSA-5vfx-8w6m-h3v4
Record: https://patchnext.com/advisories/cve-2021-41129 (revision 1, source checked 26 Oct 2026, 13:59 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pterodactyl/panel 1.6.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist pterodactyl/panel: affected >= 1.0.0, < 1.6.2; fixed in 1.6.2

## Suggested inspection (read-only)
- Packagist pterodactyl/panel: check the installed version with your package manager.

## 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 pterodactyl/panel.
- 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://github.com/advisories/GHSA-5vfx-8w6m-h3v4 (GitHub-reviewed advisory GHSA-5vfx-8w6m-h3v4 lists affected ranges: Packagist pterodactyl/panel >=1.0.0 <1.6.2)

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