Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Discourse | Discourse | < 2025.12.0 |
Related Weaknesses (CWE)
References
FAQ
What is CVE-2026-26078?
CVE-2026-26078 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 signa...
How severe is CVE-2026-26078?
CVE-2026-26078 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-26078?
Check the references section above for vendor advisories and patch information. Affected products include: Discourse Discourse.