CVE-2026-40869
Decidim amendments can be accepted or rejected by anyone
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).
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Decidim amendments can be accepted or rejected by anyone
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).
- Record
CVE-2026-40869- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-266
- Updated
- 2026-11-02
EUVDEUVD-2026-24251
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).
- Record
EUVD-2026-24251- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-w5xj-99cg-rccm
Decidim amendments can be accepted or rejected by anyone
Impact
The 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.
The only check done when accepting or rejecting amendments is whether the amendment reactions are enabled for the component: https://github.com/decidim/decidim/blob/9d6c3d2efe5a83bb02e095824ff5998d96a75eb7/decidim-core/app/permissions/decidim/permissions.rb#L107
The permission checks have been changed at 1b99136 which was introduced in released version 0.19.0. I have not investigated whether prior versions are also affected.
Patches
Not available
Workarounds
Disable amendment reactions for the amendable component (e.g. proposals).
- Record
GHSA-w5xj-99cg-rccm- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-266
- Updated
- 2026-11-02
NVD
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).
- Record
CVE-2026-40869- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-266
- Updated
- 2026-11-02
OSV
Decidim amendments can be accepted or rejected by anyone
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).
- Record
CVE-2026-40869- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-266
- Updated
- 2026-11-02
OSVGHSA-w5xj-99cg-rccm
Decidim amendments can be accepted or rejected by anyone
Impact
The 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.
The only check done when accepting or rejecting amendments is whether the amendment reactions are enabled for the component: https://github.com/decidim/decidim/blob/9d6c3d2efe5a83bb02e095824ff5998d96a75eb7/decidim-core/app/permissions/decidim/permissions.rb#L107
The permission checks have been changed at 1b99136 which was introduced in released version 0.19.0. I have not investigated whether prior versions are also affected.
Patches
Not available
Workarounds
Disable amendment reactions for the amendable component (e.g. proposals).
- Record
GHSA-w5xj-99cg-rccm- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-266
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
decidim-coreRubyGems |
0.31.0.rc1 up to 0.31.1 | 0.31.1 |
decidim-coreRubyGems |
0.19.0 up to 0.30.5 | 0.30.5 |
decidim-coreRubyGems |
0.31.0.rc1 up to 0.31.1, plus listed versions 0.31.00.31.0.rc2 |
0.31.1 |
decidim-coreRubyGems |
0.19.0 up to 0.30.5, plus listed versions 0.19.10.20.00.20.10.21.00.22.0 Show 45 moreShow less0.23.00.23.10.23.1.rc10.23.20.23.30.23.40.23.50.23.60.24.00.24.0.rc10.24.0.rc20.24.10.24.20.24.30.25.00.25.0.rc10.25.0.rc20.25.0.rc30.25.0.rc40.25.10.25.20.26.00.26.0.rc10.26.0.rc20.26.10.26.100.26.20.26.30.26.40.26.50.26.70.26.80.26.90.27.00.27.0.rc10.27.0.rc20.27.10.27.100.27.20.27.30.27.40.27.50.27.60.27.70.27.8 |
0.30.5 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-40869 is a high vulnerability (CVSS 7.5) in Decidim, published April 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. Fixed in decidim-core 0.31.1.
References
github.com/decidim/decidim/security/advisories/GHSA-w5xj-99cg-rccm
nvd.nist.gov/vuln/detail/CVE-2026-40869
Left out here: 30 versions. The JSON record has them.