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Vulnerabilities

Vulnerability · CVE-2026-26077

Discourse is an open source discussion platform.

Published Feb 26, 2026 · catalog updated Jun 17, 2026 · Discourse is an open

Check if you run it

No confirmed exploitation is on record for CVE-2026-26077. EPSS is 1.14%. Act only if a listed version of Discourse is an open is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Discourse is an open).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
1.14%
Remediation
Advisory link
Affected products
cpe discourse/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 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., , , , ). There's no current workaround for mailpace before getting this fix.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe discourse/discourse2026.2.0

How to fix CVE-2026-26077

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-26077. EPSS is 1.14%. Act only if a listed version of Discourse is an open is installed.

Which versions are affected?

Compare what you have installed with 2026.2.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-287: Improper Authentication. EPSS 1.14%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 26, 2026 · NIST NVD

    Detected

    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 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

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 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

Sources

  • CVE.orgVulnerability recordCVE-2026-26077

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-26077

    30-day exploitation probability 1.1%

    first.org
  • NIST NVDVulnerability recordCVE-2026-26077

    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 accepted requests without a valid authentication token when no token was

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.