CVE-2026-40869Network attack vector

Authenticated amendment control via missing user authorization

Published Apr 21, 2026 · Updated Apr 21, 2026

Authorization bypass in Decidim 0.19.0 through 0.30.4 and 0.31.0.rc1 through 0.31.0 allows remote authenticated users to control amendments. The amendment permission branch returns allow whenever component.current_settings.amendment_reaction_enabled is true, without performing any user-specific authorization. Any registered user can therefore accept or reject amendments to other users' proposals and becomes a coauthor when accepting one.

CVSS severity7.5
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Decidim 0.19.0 through 0.30.4 and 0.31.0.rc1 through 0.31.0 allows remote authenticated users to control amendments. The amendment permission branch returns allow whenever component.current_settings.amendment_reaction_enabled is true, without performing any user-specific authorization. Any registered user can therefore accept or reject amendments to other users' proposals and becomes a coauthor when accepting one.

The record

CVE
CVE-2026-40869
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
Decidim
Product
Decidim
Classifications
CWE-266, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.19.0, < 0.30.5
  2. Affected versionversion=>= 0.31.0.rc1, < 0.31.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Decidim · Decidimversion=>= 0.19.0, < 0.30.5; version=>= 0.31.0.rc1, < 0.31.1

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-266Incorrect Privilege Assignment
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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