What is the CVSS score of CVE-2025-66488?

CVE-2025-66488 has a CVSS 3.1 base score of 4.6 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L. EPSS exploitation probability: 0.0%.

Which versions of Discourse are affected by CVE-2025-66488?

Organizations using versions should be aware of moderate risk from CVE-2025-66488 rated CVSS 4.6. Exploitation could compromise the security of affected deployments.

How to fix or mitigate CVE-2025-66488?

Within 30 days: Identify affected systems running versions and apply vendor patches as part of regular patch cycle. Monitor vendor channels for patch availability.

Discourse CVE-2025-66488

MEDIUM

Improper Encoding or Escaping of Output (CWE-116)

2026-01-28 security-advisories@github.com

XSS Discourse

4.6

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

4.6 MEDIUM

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

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

CVSS VectorGitHub Advisory

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

Low

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

CVE Published

Jan 28, 2026 - 19:16 nvd

MEDIUM 4.6

DescriptionGitHub Advisory

Discourse is an open source discussion platform. A vulnerability present in versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 affects anyone who uses S3 for uploads. While scripts may be executed, they will only be run in the context of the S3/CDN domain, with no site credentials. Versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 fix the issue. As a workaround, disallow html or xml files for uploads in authorized_extensions. For existing html xml uploads, site owners can consider deleting them.

AnalysisAI

Discourse is an open source discussion platform. A vulnerability present in versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 affects anyone who uses S3 for uploads. [CVSS 4.6 MEDIUM]

Technical ContextAI

Classified as CWE-116 (Improper Encoding or Escaping of Output). Affects Discourse. Discourse is an open source discussion platform. A vulnerability present in versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 affects anyone who uses S3 for uploads. While scripts may be executed, they will only be run in the context of the S3/CDN domain, with no site credentials. Versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 fix the issue. As a workaround, disallow html or xml files for uploads in authorized_extensions. For existing html xml uploads, site owners can consider dele

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

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CVE-2025-66488 vulnerability details – vuln.today

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