Webhook Signature Forgery Vulnerability in Discourse Open Source Platform
CVE-2026-26078

7.5HIGH

Key Information:

Vendor

Discourse
Status
Discourse
Vendor
CVE Published:
26 February 2026

What is CVE-2026-26078?

The Discourse open-source discussion platform is vulnerable to a webhook signature forgery attack when the patreon_webhook_secret site setting is not configured. Attackers can exploit this vulnerability by generating valid HMAC-MD5 signatures using an empty key, thereby allowing the injection of arbitrary webhook payloads. This can lead to unauthorized operations such as the creation, modification, or deletion of Patreon pledge data and can trigger unwanted patron-to-group synchronization. The issue has been addressed in recent updates (versions 2025.12.2, 2026.1.1, and 2026.2.0) which enforce the requirement of a non-empty secret for webhook operations. Users are also advised to configure their patreon_webhook_secret with a strong, unique value as a precautionary measure.

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Deploy the Patch

Affected Version(s)

discourse < 2025.12.2 < 2025.12.2

discourse >= 2026.1.0-latest, < 2026.1.1 < 2026.1.0-latest, 2026.1.1

discourse >= 2026.2.0-latest, < 2026.2.0 < 2026.2.0-latest, 2026.2.0

References

https://github.com/discourse/discourse/security/advisorie...
x_refsource_CONFIRM

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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