Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
4DescriptionGitHub Advisory
Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.3, 2026.2.0-latest to before 2026.2.2, and 2026.3.0-latest to before 2026.3.0, category group moderators could perform privileged actions on topics inside private categories they did not have read access to. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.
AnalysisAI
Category group moderators in Discourse versions 2026.1.0-2026.1.2, 2026.2.0-2026.2.1, and 2026.3.0-pre can perform privileged actions (such as topic moderation) on content within private categories to which they lack read access, bypassing intended access controls. This authenticated privilege escalation affects self-hosted and managed Discourse instances and has been resolved in versions 2026.1.3, 2026.2.2, and 2026.3.0+. …
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Vulnerability AssessmentAI
| Risk Assessment | The CVSS 5.3 score reflects low-to-medium severity: the attack requires authentication (PR:L), network access (AV:N), and no user interaction, yielding limited confidentiality and integrity impact (VC:L, VI:L) with no availability impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An authenticated category group moderator assigned to moderate a private category (e.g., 'Staff Only') attempts to access a topic in that category via the Discourse web UI or API. Normally, the topic would be invisible because the moderator lacks read permission. … |
| Remediation | Upgrade immediately to patched versions: 2026.1.3, 2026.2.2, or 2026.3.0 and later depending on the currently deployed major version track. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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EUVD-2026-17553