Decidim up to 0.30.4/0.31.0 privileges assignment

Summaryinfo

A vulnerability classified as problematic was found in Decidim up to 0.30.4/0.31.0. This issue affects some unknown processing. Executing a manipulation can lead to privileges assignment. This vulnerability is tracked as CVE-2026-40869. The attack can be launched remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in Decidim up to 0.30.4/0.31.0 and classified as problematic. This vulnerability affects an unknown function. The manipulation with an unknown input leads to a privileges assignment vulnerability. The CWE definition for the vulnerability is CWE-266. A product incorrectly assigns a privilege to a particular actor, creating an unintended sphere of control for that actor. As an impact it is known to affect integrity. CVE summarizes:

Decidim is a participatory democracy framework. Starting in version 0.19.0 and prior to versions 0.30.5 and 0.31.1, a vulnerability allows any registered and authenticated user to accept or reject any amendments. The impact is on any users who have created proposals where the amendments feature is enabled. This also elevates the user accepting the amendment as the author of the original proposal as people amending proposals are provided coauthorship on the coauthorable resources. Versions 0.30.5 and 0.31.1 fix the issue. As a workaround, disable amendment reactions for the amendable component (e.g. proposals).

The advisory is available at github.com. This vulnerability was named CVE-2026-40869 since 04/15/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

Upgrading to version 0.30.5 or 0.31.1 eliminates this vulnerability. Applying the patch 1b99136a1c7aa02616a0b54a6ab88d12907a57a9 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• Decidim

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.30.0
• 0.30.1
• 0.30.2
• 0.30.3
• 0.30.4
• 0.31.0

License

• open-source

Website

• Product: https://github.com/decidim/decidim/

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