What is the CVSS score of CVE-2026-26077?

CVE-2026-26077 has a CVSS 3.1 base score of 6.5 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L. EPSS exploitation probability: 0.1%.

Which versions of Discourse are affected by CVE-2026-26077?

Organizations using Discourse should be aware of notable risk from CVE-2026-26077, a improper authentication vulnerability rated CVSS 6.5. This could allow unauthorized access to protected resources.

How to fix or mitigate CVE-2026-26077?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Audit authentication configurations.

Discourse CVE-2026-26077

MEDIUM

Improper Authentication (CWE-287)

2026-02-26 security-advisories@github.com

Authentication Bypass Discourse

6.5

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

6.5 MEDIUM

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

Low

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

CVE Published

Feb 26, 2026 - 15:17 nvd

MEDIUM 6.5

DescriptionGitHub Advisory

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, several webhook endpoints (SendGrid, Mailjet, Mandrill, Postmark, SparkPost) in the WebhooksController accepted requests without a valid authentication token when no token was configured. This allowed unauthenticated attackers to forge webhook payloads and artificially inflate user bounce scores, potentially causing legitimate user emails to be disabled. The Mailpace endpoint had no token validation at all. Starting in versions 2025.12.2, 2026.1.1, and 2026.2.0, all webhook endpoints reject requests with a 406 response when no authentication token is configured. As a workaround, ensure that webhook authentication tokens are configured for all email provider integrations in site settings (e.g., sendgrid_verification_key, mailjet_webhook_token, postmark_webhook_token, sparkpost_webhook_token). There's no current workaround for mailpace before getting this fix.

AnalysisAI

Unauthenticated attackers can submit forged webhook payloads to multiple email provider integrations in Discourse versions prior to 2025.12.2, 2026.1.1, and 2026.2.0 when authentication tokens are not configured, allowing them to artificially inflate user bounce scores and disable legitimate user accounts. The vulnerability affects webhook endpoints for SendGrid, Mailjet, Mandrill, Postmark, and SparkPost, with Mailpace having no token validation whatsoever. Administrators should immediately configure webhook authentication tokens for all email provider integrations as a workaround until patching is available.

Technical ContextAI

Classified as CWE-287 (Improper Authentication). Affects Discourse. Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, several webhook endpoints (SendGrid, Mailjet, Mandrill, Postmark, SparkPost) in the WebhooksController accepted requests without a valid authentication token when no token was configured. This allowed unauthenticated attackers to forge webhook payloads and artificially inflate user bounce scores, potentially causing legitimate user emails to be disabled. The Mailpace endpoint had no token vali