CVE-2025-66407: Weblate has Server-Side Request Forgery vulnerability
Impact The Create Component functionality in Weblate allows authorized users to add new translation components by specifying both a version control system and a source code repository URL to pull from. However, the repository URL field is not validated or sanitized, allowing an attacker to supply arbitrary protocols, hostnames, and IP addresses, including localhost, internal network addresses, and local filenames.
When the Mercurial version control system is selected, Weblate exposes the full server-side HTTP response for the provided URL. This effectively creates a server-side request forgery (SSRF) primitive that can probe internal services and return their contents. In addition to accessing internal HTTP endpoints, the behavior also enables local file enumeration by attempting file:// requests. While file contents may not always be returned, the application’s error messages clearly differentiate between files that exist and files that do not, revealing information about the server’s filesystem layout.
In cloud environments, this behavior is particularly dangerous, as internal-only endpoints such as cloud metadata services may be accessible, potentially leading to credential disclosure and full environment compromise.
Patches
This has been addressed in the Weblate 5.15 release.
https://github.com/WeblateOrg/weblate/pull/17103 https://github.com/WeblateOrg/weblate/pull/17102
Workarounds
Removing Mercurial from VCSBACKENDS avoids this vulnerability, as the Git backend is not affected. The Git backend was already configured to block the file protocol and does not expose the HTTP response content in the error message.
References Thanks to Jason Marcello for responsible disclosure.
Other sources
Weblate is a web based localization tool. The Create Component functionality in Weblate allows authorized users to add new translation components by specifying both a version control system and a source code repository URL to pull from. However, prior to version 5.15, the repository URL field is not validated or sanitized, allowing an attacker to supply arbitrary protocols, hostnames, and IP addresses, including localhost, internal network addresses, and local filenames. When the Mercurial version control system is selected, Weblate exposes the full server-side HTTP response for the provided URL. This effectively creates a server-side request forgery (SSRF) primitive that can probe internal services and return their contents. In addition to accessing internal HTTP endpoints, the behavior also enables local file enumeration by attempting file:// requests. While file contents may not always be returned, the application’s error messages clearly differentiate between files that exist and files that do not, revealing information about the server’s filesystem layout. In cloud environments, this behavior is particularly dangerous, as internal-only endpoints such as cloud metadata services may be accessible, potentially leading to credential disclosure and full environment compromise. This has been addressed in the Weblate 5.15 release. As a workaround, remove Mercurial from VCSBACKENDS; the Git backend is not affected. The Git backend was already configured to block the file protocol and does not expose the HTTP response content in the error message.
— MITRE
Affected Software
Remediation
Patch Available
Patch Available
Event History
Frequently Asked Questions
What is the severity of CVE-2025-66407?
CVE-2025-66407 is classified with a moderate severity due to its potential to allow unauthorized access to repository information.
How do I fix CVE-2025-66407?
To fix CVE-2025-66407, upgrade Weblate to version 5.15 or later to mitigate the vulnerability.
Who is affected by CVE-2025-66407?
Weblate users running versions prior to 5.15 are affected by CVE-2025-66407.
What is the impact of CVE-2025-66407?
The impact of CVE-2025-66407 includes the potential for unauthorized users to add translation components with incorrect or malicious repository URLs.
When was CVE-2025-66407 reported?
CVE-2025-66407 was reported as a vulnerability before the release of Weblate version 5.15.