Summary
Decidim: Verification documents can be downloaded through reusable links
Description
Scanned identity-document images provided by participants and shown in the verification admin workflow are exposed through signed /rails/active_storage/disk/ URLs that can be fetched without any authenticated session.
Anyone who obtains one of those URLs can retrieve the document until the signature expires.
Technical description
This issue comes from the verification admin UI exposing scanned documents through reusable Active Storage disk links. Verification-document images are rendered with variant_url(...), which produces signed /rails/active_storage/disk/... links instead of routing the file through an authorization-checking controller. Because Decidim configures Active Storage service URLs to remain valid for seven days, the URL itself becomes the credential for that period.
The affected files are verification_attachment blobs on Decidim::Authorization, and the admin review pages embed those signed URLs directly into the HTML for pending and confirmation views.
Reproduction steps:
Create a fresh verification document as a normal user.
1.1. Open http://localhost:3001/users/sign_in.
1.2. Open http://localhost:3001/id_documents/authorizations/new.
1.3. Submit an id_documents verification request with an image attachment.Open the admin review page that renders the attachment.
2.1. Sign out.
2.2. Sign back in as [email protected].
2.3. Try http://localhost:3001/admin/id_documents.Harvest the signed Active Storage URL.
3.1. Open DevTools Network before loading the review page.
3.2. Reload the page.
3.3. Copy one request URL matchinghttp://localhost:3001/rails/active_storage/disk/<SIGNED_TOKEN>/<FILENAME>.Replay the file URL without any Decidim session.
4.1. Open a private window or a second browser where you are not signed in to Decidim.
4.2. Paste the exact copied /rails/active_storage/disk/... URL.
4.3. Confirm the verification image still loads.
Workarounds
Disable the "Identity documents" verification
Reference
OWASP A01:2021 Broken Access Control
Credits
This issue was discovered in a security audit organized by the Decidim Association and made by Radically Open Security against Decidim financed by NGI.
Impact
- This only applies to Organizations using the "Identity documents" verification
- Any party that obtains one of these URLs can download the underlying scanned identity document for the lifetime of the signed link without needing to authenticate as the reviewing admin.
- In the reproduced case, that replay window was about seven days, which is long enough for routine leakage channels such as copied links, screenshots, logs, browser history, and support workflows to become realistic exfiltration paths.
- This raises the risk of leakage through browser history, screenshots, copy-paste, support tickets, logs, analytics tooling, malicious browser extensions, or any other channel that captures full URLs.
- Because the affected files are identity-verification documents, the exposed data can include highly sensitive personal information.
CVE-2026-45378 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.30.9, 0.31.5, 0.32.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-45378? CVE-2026-45378 is a high-severity security vulnerability in decidim-verifications (rubygems), affecting versions < 0.30.9. It is fixed in 0.30.9, 0.31.5, 0.32.0.
- How severe is CVE-2026-45378? CVE-2026-45378 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of decidim-verifications are affected by CVE-2026-45378? decidim-verifications (rubygems) versions < 0.30.9 is affected.
- Is there a fix for CVE-2026-45378? Yes. CVE-2026-45378 is fixed in 0.30.9, 0.31.5, 0.32.0. Upgrade to this version or later.
- Is CVE-2026-45378 exploitable, and should I be worried? Whether CVE-2026-45378 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-45378 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-45378?
- Upgrade
decidim-verificationsto 0.30.9 or later - Upgrade
decidim-verificationsto 0.31.5 or later - Upgrade
decidim-verificationsto 0.32.0 or later
- Upgrade