CVE-2026-40870: Decidim missing authorization in comments API

CVE-2026-40870 · Severity: high · CVSS 7.5 · Published 2026-04-14

Decidim is an open-source participatory democracy platform used by organizations and governments to facilitate public debate and decision-making. A security flaw in its API allows unauthorized users to access all commentable resources, potentially exposing private data from restricted participation spaces. This could lead to the disclosure of sensitive internal discussions or community feedback intended to be private.

Vendors: Decidim.

Quick answers

Is CVE-2026-40870 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-40870 being exploited in the wild.
How severe is CVE-2026-40870?
High severity, with a CVSS score of 7.5, published 14 April 2026.
Which products and versions are affected?
Decidim Comments >= 0.0.1, < 0.30.5; > 0.31.0.rc1, < 0.31.1.
Is there a fix for CVE-2026-40870?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-40870 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-40870?
Check whether you run Decidim Comments at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A missing authorization vulnerability (CWE-862) exists in Decidim's GraphQL API. The root-level 'commentable' field fails to perform permission checks, allowing any user—including unauthenticated ones if the /api endpoint is public—to query and retrieve data from any commentable resource on the platform. This bypasses intended access controls for private participation spaces. The vulnerability is exploitable over the network without user interaction. Patches are available in versions 0.30.5 and 0.31.1. Workarounds include restricting /api access to authenticated users or specific IP ranges via middleware or web server configuration.

Affected products

  • Decidim decidim-api >= 0.0.1, < 0.30.5; > 0.31.0.rc1, < 0.31.1
  • Decidim decidim-comments >= 0.0.1, < 0.30.5; > 0.31.0.rc1, < 0.31.1

Identifiers

  • CVE-2026-40870
  • GHSA-ghmh-q25g-gxxx

Timeline

  • 2026-04-13: disclosed: Vulnerability reported to Decidim
  • 2026-04-14: advisory: GitHub Advisory published
  • 2026-04-21: other: NVD published CVE-2026-40870

References

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