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CVE-2026-33393

4.3 · MEDIUM

Discourse is an open-source discussion platform.

Published Mar 19, 2026CWE-284EPSS 0.36%

Overview

CVE-2026-33393 is a medium-severity vulnerability. It was published on March 19, 2026 and has a CVSS 3.1 base score of 4.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/discourse/discourse/commit/80b19c15fe9c7bc890d1a54f454c8446312ac6d2GitHubgithub.com/discourse/discourse/commit/d8467b9fbb3d9ed6047b4e508d3fef88a37b8a02GitHubgithub.com/discourse/discourse/commit/f99099cfbc6b76fe39d6fa2daa48efd69497fb8eGitHubgithub.com/discourse/discourse/security/advisories/GHSA-95r5-p6qr-hgw6

How CyberStrike helps

Frequently asked questions

What is CVE-2026-33393?

CVE-2026-33393 is a medium-severity vulnerability. It was published on March 19, 2026 and has a CVSS 3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-33393?

This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-33393?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-33393?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-33393 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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