What is the CVSS score of CVE-2026-33393?

CVE-2026-33393 has a CVSS 3.1 base score of 4.3 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Discourse are affected by CVE-2026-33393?

Organizations using Discourse should be aware of moderate risk from CVE-2026-33393, a improper access control vulnerability rated CVSS 4.3.

Discourse CVE-2026-33393

MEDIUM

Improper Access Control (CWE-284)

2026-03-19 security-advisories@github.com

Authentication Bypass Discourse

4.3

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

4.3 MEDIUM

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

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

CVSS VectorGitHub Advisory

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

Lifecycle Timeline

Analysis Generated

Mar 19, 2026 - 22:30 vuln.today

CVE Published

Mar 19, 2026 - 22:16 nvd

MEDIUM 4.3

DescriptionGitHub Advisory

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.

AnalysisAI

A remote code execution vulnerability in Discourse (CVSS 4.3). Remediation should follow standard vulnerability management procedures.

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Vulnerability AssessmentAI

Risk Assessment	CVSS 4.3. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker could exploit this vulnerability in Discourse to compromise the security of affected deployments, potentially impacting confidentiality, integrity, or availability.
Remediation	Monitor vendor channels for patch availability. Detailed patch versions, workarounds, and compensating controls in full report.

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

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CVE-2026-33393 vulnerability details – vuln.today

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Discourse CVE-2026-33393

Severity by source

CVSS VectorGitHub Advisory

Lifecycle Timeline

DescriptionGitHub Advisory

AnalysisAI

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