CVE-2026-45378 is a high-severity (CVSS 7.5) Information Exposure vulnerability in decidim-verifications. A fix is available for decidim-verifications — see the affected versions and patch details below.
Decidim: Verification documents can be downloaded through reusable links
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45378.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
decidim-verifications💎decidim-verifications💎decidim-verificationsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
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 matching
http://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.
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.
Patches
See https://github.com/decidim/decidim/pull/16680
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | decidim-verifications | all versions | 0.30.9bundle update decidim-verifications --conservative |
| 💎RubyGems | decidim-verifications | ≥ 0.31.0.rc1&&< 0.31.5 | 0.31.5bundle update decidim-verifications --conservative |
| 💎RubyGems | decidim-verifications | ≥ 0.32.0.rc1&&< 0.32.0 | 0.32.0bundle update decidim-verifications --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for decidim-verifications, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update decidim-verifications to 0.30.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45378 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2026-45378 in your dependencies?
Find it across RubyGems, including transitive dependencies.