What’s Vulnerable › Vulnerabilities
CVE-2026-26078: Discourse has authentication bypass vulnerability in the Patreon plugin webhook endpoint
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-02-26 · updated 2026-06-17
- Weakness: CWE-639
Description
Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, when the `patreon_webhook_secret` site setting is blank, an attacker can forge valid webhook signatures by computing an HMAC-MD5 with an empty string as the key. Since the request body is known to the sender, the attacker can produce a matching signature and send arbitrary webhook payloads. This allows unauthorized creation, modification, or deletion of Patreon pledge data and triggering patron-to-group synchronization. This vulnerability is patched in versions 2025.12.2, 2026.1.1, and 2026.2.0. The fix rejects webhook requests when the webhook secret is not configured, preventing signature forgery with an empty key. As a workaround, configure the `patreon_webhook_secret` site setting with a strong, non-empty secret value. When the secret is non-empty, an attacker cannot forge valid signatures without knowing the secret.
Affected products
- discourse: before 2025.12.0; from 2026.1.0 before 2026.1.1; 2026.2.0 — fixed in 2025.12.0, 2026.1.1
How to fix
Upgrade to a fixed version: discourse 2025.12.0, 2026.1.1. Check the vendor advisory for mitigations.
References
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