EUVD-2026-17557
CVSS Vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/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
3Description
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, users who lost access to a topic (e.g., removed from a private category group) could still interact with polls in that topic, including voting and toggling poll status. No content was exposed, but users could modify poll state in topics they should no longer have access to. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.
Analysis
Discourse versions 2026.1.0 through 2026.1.2, 2026.2.0 through 2026.2.1, and 2026.3.0-beta retain unauthorized poll interaction capabilities for users who have lost access to private topics, allowing them to vote on and toggle poll status despite removal from category group membership. While no topic content is exposed, the vulnerability permits state modification in topics to which access should have been revoked, violating the intended access control model. …
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External POC / Exploit Code
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