CVE-2026-39845: Weblate SSRF Vulnerability

MODERATE
Advisory Identifier: GHSA-f8hv-g549-hwg2
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CVSS 4.1
CWE-918
Published
Advisory Summary

CVE-2026-39845 is a MODERATE (CVSS 4.1) ssrf vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Weblate libraries in the PyPI ecosystem. The issue involves ssrf via the webhook add-on using unprotected fetch_url(). Remediation is available by upgrading affected packages to version 5.17.

CVE-2026-39845 at a Glance

CVE Identifier CVE-2026-39845
GHSA Identifier GHSA-f8hv-g549-hwg2
Severity MODERATE
CVSS v3.1 Base Score 4.1
CWE Classification CWE-918: Server-Side Request Forgery (SSRF)
Affected Product Weblate
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 4.1

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

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required High (PR:H)
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-2026-39845

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: 5.17 
pip install Weblate>=5.17
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-2026-39845, 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 5.17), 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 webhook add-on did not utilize existing SSRF protection. ### Patches * https://github.com/WeblateOrg/weblate/pull/18815 ### Workarounds Disabling the add-on would avoid misusing this. ### References Thanks to @Lihfdgjr for reporting this via GitHub.

CVE-2026-39845 Affected Weblate Versions

1 component(s)
Fixed Versions:
5.17
Product / Package Ecosystem Affected Versions Fixed Version
Weblate
pypi/Weblate
PyPI
< 5.17
5.17

References

GitHub Advisory / Wiki ADVISORY
https://github.com/WeblateOrg/weblate/security/advisories/GHSA-f8hv-g549-hwg2
NVD — CVE-2026-39845 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39845
Weblate Source Repository REPOSITORY
https://github.com/WeblateOrg/weblate/pull/18815
Weblate Source Repository REPOSITORY
https://github.com/WeblateOrg/weblate
Weblate Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/weblate/PYSEC-2026-156.yaml

Frequently Asked Questions

What is CVE-2026-39845?
CVE-2026-39845 is a security vulnerability in Weblate involving SSRF via the webhook add-on using unprotected fetch_url() under CWE-918: Server-Side Request Forgery (SSRF).
Which Weblate versions are affected?
Affected versions include releases prior to 5.17 across affected packages: Weblate.
What version fixes CVE-2026-39845?
Upgrading to 5.17 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Weblate affected?
Yes, Weblate is affected in releases prior to 5.17. Upgrade your dependency to 5.17 or later.
What is the CVSS score of CVE-2026-39845?
CVE-2026-39845 has a CVSS v3.1 base score of 4.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N.
What CWE is associated with CVE-2026-39845?
CVE-2026-39845 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-2026-39845?
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-f8hv-g549-hwg2",
  "modified" : "2026-06-08T19:54:41Z",
  "published" : "2026-04-16T20:45:04Z",
  "aliases" : [ "CVE-2026-39845" ],
  "summary" : "Weblate: SSRF via the webhook add-on using unprotected fetch_url()",
  "details" : "### Impact\nThe webhook add-on did not utilize existing SSRF protection.\n\n### Patches\n* https://github.com/WeblateOrg/weblate/pull/18815\n\n### Workarounds\nDisabling the add-on would avoid misusing this.\n\n### References\nThanks to @Lihfdgjr for reporting this via GitHub.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "Weblate"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.17"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/WeblateOrg/weblate/security/advisories/GHSA-f8hv-g549-hwg2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-39845"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/WeblateOrg/weblate/pull/18815"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/WeblateOrg/weblate"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/weblate/PYSEC-2026-156.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-16T20:45:04Z",
    "nvd_published_at" : "2026-04-15T19:16:36Z"
  }
}