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Bypass of domain hijacking protections

Moderate
stsewd published GHSA-gx98-95mq-3jx6 Nov 4, 2025

Package

Read the Docs (Python)

Affected versions

<15.5.1

Patched versions

15.5.1

Description

Impact

This vulnerability could have allowed an attacker to hijack some of our subdomains under readthedocs.com/readthedocs.org. This was due to our existing protections disallowing subdomains of app.readthedocs.org/com only.

Users of https://readthedocs.org/ and https://readthedocs.com/ do not need to take any further action, we have taken measures to ensure that the security issue is now fully fixed. This issue was discovered by a member of our team, and we have seen no signs that this vulnerability was abused in the wild.

Custom installations

We don't officially support custom installations of Read the Docs, but If you are using a custom installation, we recommend you to upgrade. If your domain includes a country code TLD, like domain.co.uk, you'll need to override the RTD_RESTRICTED_DOMAINS setting, otherwise the application will block all custom domains that end with co.uk.

Patches

This vulnerability has been patched with our 15.5.1 release.

References

For more information

If you have any questions or comments about this advisory, email us at [email protected] (PGP)

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N

CVE ID

No known CVE

Weaknesses

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Learn more on MITRE.

Credits