CVE-2025-66407: Weblate Weblate Has A Server-Side Request Vulnerability

MODERATE
Advisory Identifier: GHSA-hfpv-mc5v-p9mm
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CVSS 5.0
CWE-918 CWE-352
Published
Advisory Summary

CVE-2025-66407 is a MODERATE (CVSS 5.0) weblate has a server-side request vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Weblate libraries in the PyPI ecosystem. The issue involves weblate has a server-side request forgery issue. Remediation is available by upgrading affected packages to version 5.15.

CVE-2025-66407 at a Glance

CVE Identifier CVE-2025-66407
GHSA Identifier GHSA-hfpv-mc5v-p9mm
Severity MODERATE
CVSS v3.1 Base Score 5.0
CWE Classification CWE-918: Server-Side Request Forgery (SSRF)
Affected Product Weblate
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.0

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2025-66407

To remediate this vulnerability, upgrade all affected Weblate dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Weblate fixed: 5.15 
pip install Weblate>=5.15
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show Weblate

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2025-66407, inspect your installed packages using pip:

pip show Weblate

Analyze the terminal output to locate any version of Weblate in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.15), your application is affected.

Note: The pip show Weblate command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where 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. In Weblate, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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 [VCS_BACKENDS](https://docs.weblate.org/en/latest/admin/config.html#vcs-backends) 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.

CVE-2025-66407 Affected Weblate Versions

1 component(s)
Fixed Versions:
5.15
Product / Package Ecosystem Affected Versions Fixed Version
Weblate
pypi/Weblate
PyPI
< 5.15
5.15

References

GitHub Advisory / Wiki ADVISORY
https://github.com/WeblateOrg/weblate/security/advisories/GHSA-hfpv-mc5v-p9mm
NVD — CVE-2025-66407 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-66407
Weblate Source Repository REPOSITORY
https://github.com/WeblateOrg/weblate/pull/17102
Weblate Source Repository REPOSITORY
https://github.com/WeblateOrg/weblate/pull/17103
Weblate Source Repository REPOSITORY
https://github.com/WeblateOrg/weblate
Weblate Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/weblate/PYSEC-2025-231.yaml

Frequently Asked Questions

What is CVE-2025-66407?
CVE-2025-66407 is a security vulnerability in Weblate involving Weblate has a Server-Side Request Forgery issue under CWE-918: Server-Side Request Forgery (SSRF).
Which Weblate versions are affected?
Affected versions include releases prior to 5.15 across affected packages: Weblate.
What version fixes CVE-2025-66407?
Upgrading to 5.15 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Weblate affected?
Yes, Weblate is affected in releases prior to 5.15. Upgrade your dependency to 5.15 or later.
What is the CVSS score of CVE-2025-66407?
CVE-2025-66407 has a CVSS v3.1 base score of 5.0 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N.
What CWE is associated with CVE-2025-66407?
CVE-2025-66407 is classified under CWE-918: Server-Side Request Forgery (SSRF) (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.).
How can I check PyPI dependencies for CVE-2025-66407?
Run the dependency tree command: 'pip show Weblate'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hfpv-mc5v-p9mm",
  "modified" : "2026-05-26T16:41:13Z",
  "published" : "2026-05-26T16:41:13Z",
  "aliases" : [ "CVE-2025-66407" ],
  "summary" : "Weblate has a Server-Side Request Forgery issue",
  "details" : "### Impact\nThe 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.\n\nWhen 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.\n\n\n\nIn 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.\n\n### Patches\n\nThis has been addressed in the Weblate 5.15 release.\n\n* https://github.com/WeblateOrg/weblate/pull/17103\n* https://github.com/WeblateOrg/weblate/pull/17102\n\n### Workarounds\n\nRemoving Mercurial from [VCS_BACKENDS](https://docs.weblate.org/en/latest/admin/config.html#vcs-backends) 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.\n\n### References\nThanks to Jason Marcello for responsible disclosure.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "Weblate"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.15"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/WeblateOrg/weblate/security/advisories/GHSA-hfpv-mc5v-p9mm"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-66407"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/WeblateOrg/weblate/pull/17102"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/WeblateOrg/weblate/pull/17103"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/WeblateOrg/weblate"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/weblate/PYSEC-2025-231.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-352", "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-26T16:41:13Z",
    "nvd_published_at" : "2025-12-16T00:16:02Z"
  }
}