PT-2026-60074 · Rubygems · Decidim-Core

CVE-2026-45573

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Publicado

2026-07-13

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Atualizado

2026-07-13

CVSS v3.1

6.4

Média

VetorAV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Description

The 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.

Technical description

When 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. This is the source-to-sink chain:
  1. Source: attacker-controlled subscription.endpoint in the JSON body posted to POST /notifications subscriptions.
  2. Persistence: params[:endpoint] is stored under user.notification settings["subscriptions"].
  3. Retrieval: user.notifications subscriptions.values returns that stored endpoint later.
  4. Sink: build payload sets endpoint: subscription["endpoint"].
  5. Outbound request: WebPush.payload send(**payload) uses the attacker-supplied endpoint as the destination.
One spec asserts that the endpoint is persisted exactly as supplied:
ruby
# decidim-core/spec/services/decidim/notifications subscriptions persistor spec.rb
expect(user.notifications subscriptions["auth code 121"]["endpoint"]).to eq(params[:endpoint])
Another spec asserts that SendPushNotification passes the stored endpoint into WebPush.payload send:
ruby
# decidim-core/spec/services/decidim/send push notification spec.rb
first notification payload = {
 message:,
 endpoint: subscriptions["auth key 1"]["endpoint"],
 p256dh: subscriptions["auth key 1"]["p256dh"],
 auth: subscriptions["auth key 1"]["auth"],
 vapid: a hash including(...)
}
expect(WebPush).to receive(:payload send).with(first notification payload)

Impact

  • In a configured deployment, an authenticated user can register an attacker-controlled or otherwise unauthorized HTTPS URL.
  • The server then sends outbound POST requests there whenever a notification is pushed.
  • This is a stored, mostly blind SSRF primitive: useful for outbound interaction with attacker infrastructure and, where routable, internal HTTPS services.
  • Notification metadata is disclosed to the supplied endpoint through the encrypted web push request path.

Patches

See https://github.com/decidim/decidim/pull/16714.

Workarounds

Disable the push notifications feature by removing the VAPID keys in the server.

Resource

SSRF

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.

Correção

SSRF

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Enumeração de Fraquezas

CWE-918

Identificadores relacionados

CVE-2026-45573
GHSA-2G9C-VF8H-PRXX

Produtos afetados

Decidim-Core