GEM · JULY 2026 · EARLY WARNING

Decidim Gem Vulnerability: Potential SSRF via Push Subscription Endpoint

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.

GHSA-2G9C-VF8H-PRXXSeverity: HIGH

An early warning has been issued regarding a potential vulnerability in the Decidim gem that could allow an authenticated, stored, mostly blind SSRF attack via the push subscription endpoint.

What happened

Reportedly, the Decidim gem's push subscription endpoint allows storing an attacker-controlled delivery URL, enabling a potential SSRF attack to arbitrary HTTPS endpoints reachable from the app server. This vulnerability appears to affect various versions of the gem, as detailed in the provided data. It is recommended to review and sanitize the push subscription endpoints in your Decidim deployment to prevent storing unauthorized URLs. For more detailed version information and fixes, consult the primary sources.

How 0Day mitigates this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If decidim is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

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