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, when the hidden prioritize_full_name_in_ux site setting is enabled (defaults to false, requires console access to change), user and group display names are rendered without HTML escaping in several assignment-related UI paths. This allows users with assign permission to inject arbitrary HTML/JavaScript that executes in the browser of any user viewing an affected topic. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.
CVSS Details
- CVSS 4.0 Base Score: 2.1 (LOW)
- CVSS 4.0 Vector: (CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/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)
- CVSS 3.1 Base Score: 5.4
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N)
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