{"id":"GHSA-2g9c-vf8h-prxx","summary":"Decidim: Push subscriptions can be abused for server-side requests","details":"## Description\n\nThe push-subscription endpoint stores an attacker-controlled delivery URL, and the notification send path becomes an outbound-request sink when VAPID delivery is enabled. The practical result is an authenticated, stored, mostly blind SSRF primitive to arbitrary HTTPS endpoints reachable from the app server.\n\n## Technical description\n \nWhen VAPID delivery is enabled, the notification subscription flow stores the client-supplied push endpoint without checking that it belongs to an approved push service. The send path later passes that stored URL to `WebPush.payload_send`, turning the subscription into an attacker-controlled outbound request destination.\nThis is the source-to-sink chain:\n\n1. Source: attacker-controlled `subscription.endpoint` in the JSON body posted to `POST /notifications_subscriptions`.\n2. Persistence: `params[:endpoint]` is stored under `user.notification_settings[\"subscriptions\"]`.\n3. Retrieval: `user.notifications_subscriptions.values` returns that stored endpoint later.\n4. Sink: `build_payload` sets `endpoint: subscription[\"endpoint\"]`.\n5. Outbound request: `WebPush.payload_send(**payload)` uses the attacker-supplied endpoint as the\ndestination.\n\nOne spec asserts that the endpoint is persisted exactly as supplied:\n\n```ruby\n# decidim-core/spec/services/decidim/notifications_subscriptions_persistor_spec.rb\nexpect(user.notifications_subscriptions[\"auth_code_121\"][\"endpoint\"]).to eq(params[:endpoint])\n```\n\nAnother spec asserts that `SendPushNotification` passes the stored endpoint into `WebPush.payload_send`:\n\n```ruby\n# decidim-core/spec/services/decidim/send_push_notification_spec.rb\nfirst_notification_payload = {\n  message:,\n  endpoint: subscriptions[\"auth_key_1\"][\"endpoint\"],\n  p256dh: subscriptions[\"auth_key_1\"][\"p256dh\"],\n  auth: subscriptions[\"auth_key_1\"][\"auth\"],\n  vapid: a_hash_including(...)\n}\nexpect(WebPush).to receive(:payload_send).with(first_notification_payload)\n```\n\n### Impact\n\n- In a configured deployment, an authenticated user can register an attacker-controlled or otherwise unauthorized HTTPS URL.\n- The server then sends outbound `POST` requests there whenever a notification is pushed.\n- This is a stored, mostly blind SSRF primitive: useful for outbound interaction with attacker infrastructure and, where routable, internal HTTPS services.\n- Notification metadata is disclosed to the supplied endpoint through the encrypted web push request path.\n\n### Patches\n\nSee https://github.com/decidim/decidim/pull/16714.\n\n### Workarounds\n\nDisable the push notifications feature by removing the VAPID keys in the server.\n\n### Resource\n\nSSRF\n\n### Credits\n\nThis issue was discovered in a security audit organized by the [Decidim Association](https://decidim.org) and made by [Radically Open Security](https://www.radicallyopensecurity.com/) against Decidim financed by [NGI](https://ngi.eu/).","aliases":["CVE-2026-45573"],"modified":"2026-07-13T17:41:46.723830Z","published":"2026-07-13T17:19:17Z","database_specific":{"cwe_ids":["CWE-918"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-07-13T17:19:17Z","nvd_published_at":null},"references":[{"type":"WEB","url":"https://github.com/decidim/decidim/security/advisories/GHSA-2g9c-vf8h-prxx"},{"type":"WEB","url":"https://github.com/decidim/decidim/pull/16714"},{"type":"PACKAGE","url":"https://github.com/decidim/decidim"}],"affected":[{"package":{"name":"decidim-core","ecosystem":"RubyGems","purl":"pkg:gem/decidim-core"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.30.9"}]}],"versions":["0.0.1","0.0.1.alpha1","0.0.1.alpha2","0.0.1.alpha3","0.0.1.alpha4","0.0.1.alpha5","0.0.1.alpha6","0.0.1.alpha7","0.0.1.alpha8","0.0.1.alpha9","0.0.2","0.0.3","0.0.5","0.0.6","0.0.7","0.0.8.1","0.1.0","0.10.0","0.10.1","0.11.0.pre1","0.11.1","0.11.2","0.12.0","0.12.0.pre","0.12.1","0.12.2","0.13.0","0.13.0.pre1","0.13.1","0.14.1","0.14.2","0.14.3","0.14.4","0.15.0","0.15.1","0.15.2","0.16.0","0.16.1","0.17.0","0.17.1","0.17.2","0.18.0","0.18.1","0.19.0","0.19.1","0.2.0","0.20.0","0.20.1","0.21.0","0.22.0","0.23.0","0.23.1","0.23.1.rc1","0.23.2","0.23.3","0.23.4","0.23.5","0.23.6","0.24.0","0.24.0.rc1","0.24.0.rc2","0.24.1","0.24.2","0.24.3","0.25.0","0.25.0.rc1","0.25.0.rc2","0.25.0.rc3","0.25.0.rc4","0.25.1","0.25.2","0.26.0","0.26.0.rc1","0.26.0.rc2","0.26.1","0.26.10","0.26.2","0.26.3","0.26.4","0.26.5","0.26.7","0.26.8","0.26.9","0.27.0","0.27.0.rc1","0.27.0.rc2","0.27.1","0.27.10","0.27.2","0.27.3","0.27.4","0.27.5","0.27.6","0.27.7","0.27.8","0.27.9","0.28.0","0.28.0.rc4","0.28.0.rc5","0.28.1","0.28.2","0.28.3","0.28.4","0.28.5","0.28.6","0.29.0","0.29.0.rc1","0.29.0.rc2","0.29.0.rc3","0.29.0.rc4","0.29.1","0.29.2","0.29.3","0.29.4","0.29.5","0.29.6","0.29.7","0.3.0","0.3.1","0.3.2","0.30.0","0.30.0.rc1","0.30.0.rc2","0.30.0.rc3","0.30.1","0.30.2","0.30.3","0.30.4","0.30.5","0.30.6","0.30.7","0.30.8","0.4.0","0.4.1","0.4.2","0.4.3","0.4.4","0.5.0","0.5.1","0.6.0","0.6.1","0.6.2","0.6.3","0.6.4","0.6.5","0.6.6","0.6.7","0.6.8","0.7.0","0.7.1","0.7.2","0.7.3","0.7.4","0.8.0","0.8.1","0.8.2","0.8.3","0.8.4","0.9.0","0.9.1","0.9.2","0.9.3"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-2g9c-vf8h-prxx/GHSA-2g9c-vf8h-prxx.json"}},{"package":{"name":"decidim-core","ecosystem":"RubyGems","purl":"pkg:gem/decidim-core"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.31.0.rc1"},{"fixed":"0.31.5"}]}],"versions":["0.31.0","0.31.0.rc1","0.31.0.rc2","0.31.1","0.31.2","0.31.3","0.31.4"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-2g9c-vf8h-prxx/GHSA-2g9c-vf8h-prxx.json"}},{"package":{"name":"decidim-core","ecosystem":"RubyGems","purl":"pkg:gem/decidim-core"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.32.0.rc1"},{"fixed":"0.32.0"}]}],"versions":["0.32.0.rc1","0.32.0.rc2","0.32.0.rc3"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-2g9c-vf8h-prxx/GHSA-2g9c-vf8h-prxx.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"}]}