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CVE-2026-45573 medium CVSS 6.4

SSRF (Server-Side Request Forgery) in decidim-core (CVE-2026-45573)

Summary

SSRF in decidim-core (CVE-2026-45573). Risk of unauthorized operations or information disclosure. Exploitable via POST /notifications_subscriptions. Mitigation: upgrade to 0.32.0 or later.

Original description

The description as published by the source.

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:

# 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 `SendPushNot…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-45573 has been found in decidim-core.
Attackers can target a specific entry point like POST /notifications_subscriptions over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.4/10.
What to do: upgrade decidim-core to 0.32.0 or later.
If unsure, ask your IT team or search "decidim-core CVE-2026-45573" on the vendor's site.

CVE-2026-45573 (decidim-core) — CWE-918 / CVSS v3 6.4
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /notifications_subscriptions / WebPush.payload_send / subscription.endpoint / user.notifications_subscriptions.values
Patched: 0.32.0 — apply immediately
Workaround: Disable the push notifications feature by removing the VAPID keys in the server.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

SSRF (CWE-918) exists in decidim-core. Attackers reach the vulnerable code path via POST /notifications_subscriptions.

📍 Affected scope

Check the vendor advisory for the affected versions of decidim-core. Attack surface: POST /notifications_subscriptions / WebPush.payload_send / subscription.endpoint / user.notifications_subscriptions.values.

🔥 Severity

Severity: Medium (CVSS 6.4/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 0.32.0.

🛡️ Workaround

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

🔍 Detection

Search webserver/proxy logs for unusual POST /notifications_subscriptions requests with malformed payloads or SQL meta-characters. Run grep -r 'decidim-core' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'decidim-core' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で decidim-core を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Hunt for indicators of compromise detect 
    grep 'POST /notifications_subscriptions' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /notifications_subscriptions への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Apply temporary workaround mitigate 
    Disable the push notifications feature by removing the VAPID keys in the server.

    パッチが適用されるまでの応急処置として、Disable the push notifications feature by removing the VAPID keys in the server. を実施。回避策の副作用 (機能低下) を確認した上で。

  4. 4
    Apply patch patch 
    Upgrade decidim-core to 0.32.0

    ステージング環境で 0.32.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。

  5. 5
    Post-deployment verification verify 
    Replay attack against POST /notifications_subscriptions on staging to confirm patch closes the vector

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

rubygems decidim-core
[{"type":"ECOSYSTEM","events":[{"introduced":"0.32.0.rc1"},{"fixed":"0.32.0"}]}]

References

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