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CVE-2026-33393

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CVE-2026-33393

Published: Mar 19, 2026

Modified: Mar 20, 2026

PUBLISHED

CVSS v3.1

4.3

MEDIUM

Description

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.

VendorProductVersions

discourse

discourse

affected
>= 2026.1.0-latest, < 2026.1.2
affected
>= 2026.2.0-latest, < 2026.2.1
affected
= 2026.3.0-latest

Weaknesses (CWE)

CWE-284

CVSS v3.1 Details

CVSS v3.1 Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

References

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