CVE-2026-40869

Description

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).

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS — Exploit Prediction

0.0004

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-266 CWE-266

Affected Products

Vendor	Product	Versions
decidim	decidim	0.19.0 — 0.30.5
decidim	decidim	0.31.0 — 0.31.1

References

Advisories & Patches

https://github.com/decidim/decidim/commit/1b99136a1c7aa02616a0b54a6ab88d12907a57a9 https://github.com/decidim/decidim/security/advisories/GHSA-w5xj-99cg-rccm

Frequently Asked Questions

What is CVE-2026-40869? +

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). It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-40869? +

CVE-2026-40869 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0004, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-40869? +

CVE-2026-40869 affects products from decidim, specifically: decidim. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-40869? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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