CVE-2026-12566
Received Received - Intake
Docker Registry Authentication Endpoint Spoofing via Unvalidated Realm Parameter

Publication date: 2026-06-17

Last updated on: 2026-06-17

Assigner: Black Lantern Security

Description
The docker_pull module uses the realm parameter from a Docker registry's WWW-Authenticate response header as the authentication endpoint without validation. An attacker in a man-in-the-middle position between bbot and a Docker registry could modify this header to redirect the authentication request to an arbitrary endpoint, potentially leaking authentication tokens.
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Meta Information
Published
2026-06-17
Last Modified
2026-06-17
Generated
2026-06-18
AI Q&A
2026-06-18
EPSS Evaluated
N/A
NVD
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
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Executive Summary

The vulnerability exists in the docker_pull module, which uses the realm parameter from a Docker registry's WWW-Authenticate response header as the authentication endpoint without validating it.

An attacker positioned as a man-in-the-middle between the client (bbot) and the Docker registry can modify this header to redirect the authentication request to a malicious endpoint.

This redirection can lead to the leakage of authentication tokens to the attacker.

Impact Analysis

This vulnerability can lead to the leakage of authentication tokens if an attacker successfully performs a man-in-the-middle attack.

Leaked tokens could allow unauthorized access to Docker registries or other resources protected by those tokens.

However, the CVSS score is relatively low (3.1), indicating that exploitation requires certain conditions such as network access and user interaction.

Compliance Impact

This vulnerability could potentially lead to the leakage of authentication tokens if an attacker successfully redirects authentication requests. Such leakage of sensitive authentication information may impact compliance with standards and regulations that require protection of authentication credentials and personal data, such as GDPR and HIPAA.

However, the provided information does not explicitly describe the direct impact on compliance with these standards or regulations.

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