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CVE-2026-33393

Discourse fixes loose hostname matching in spam host allowlist PUBLISHED

Description (CNA)

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the `allowed_spam_host_domains` check used `String#end_with?` without domain boundary validation, allowing domains like `attacker-example.com` to bypass spam protection when `example.com` was allowlisted. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 require exact match or proper subdomain match (preceded by `.`) to prevent suffix-based bypass of `newuser_spam_host_threshold`. No known workarounds are available.

Affected (CNA)

Vendor / productVersions
discourse / discourseaffected >= 2026.1.0-latest, < 2026.1.2; affected >= 2026.2.0-latest, < 2026.2.1; affected = 2026.3.0-latest

CWE

CWE-284

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.