CVE-2026-45377
Received Received - Intake

Authentication Bypass in Decidim via Active Storage URL

Publication date: 2026-07-31

Last updated on: 2026-08-01

Assigner: GitHub, Inc.

Description
Decidim is a participatory democracy framework. Prior to 0.30.9, from 0.31.0 before 0.31.5, and in 0.32.0.rc1 before 0.32.0.rc2, the normal download_your_data flow requires the requester to be logged in as the export owner, but the resulting Active Storage blob redirect URL can be replayed without authentication by anyone who obtains it. This is because Decidim::DownloadYourDataController#download_file authenticates the export owner but redirects to a signed Active Storage blob URL that is no longer bound to the owner session. This issue is fixed in versions 0.30.9, 0.31.5, and 0.32.0.rc2.

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Meta Information

Published
2026-07-31
Last Modified
2026-08-01
Generated
2026-08-01
AI Q&A
2026-08-01
EPSS Evaluated
N/A
NVD
CVE-2026-45377

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
decidim decidim to 0.30.9 (inc)
decidim decidim From 0.31.0 (inc) to 0.31.5 (exc)
decidim decidim From 0.32.0.rc1 (inc) to 0.32.0.rc2 (exc)
decidim decidim to 0.32.0.rc2 (inc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-200 The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
CWE-284 The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

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Executive Summary

This vulnerability affects Decidim, a participatory democracy framework. It allows unauthorized access to download your data exports. Normally, only the owner can download their data, but the download link can be reused by anyone who gets it, bypassing authentication. This happens because the download link is not tied to the owner's session after creation.

Detection Guidance

This vulnerability involves improper session validation in Decidim's download_your_data feature. To detect it, check if Active Storage blob URLs for user data exports lack proper authentication requirements. Review Decidim logs for unauthorized access attempts to download_your_data endpoints or Active Storage blob redirects. Verify that blob URLs are bound to user sessions and expire appropriately.

Impact Analysis

If you are a Decidim user, an attacker could access your exported data by obtaining the download link. This could expose sensitive information contained in your data export. The impact is higher if the exported data includes personal or confidential information.

Compliance Impact

This vulnerability could lead to unauthorized access to personal data, violating GDPR's principles of data protection and user consent. For HIPAA, it may risk exposing protected health information if such data is included in exports. Organizations using affected versions must address this to maintain compliance.

Mitigation Strategies

Upgrade Decidim to a patched version: 0.30.9, 0.31.5, or 0.32.0.rc2 or later. Review Active Storage blob URLs to ensure they are no longer accessible without authentication. Monitor for unauthorized access to download_your_data exports.

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