MISP contains an incomplete authorization check in the discussion posting functionality. When a user submits a post to a thread or replies to an existing post, the application only verified whether the target thread was restricted to a single organization (org-only distribution). It did not enforce the full thread access control list, including sharing-group membership and event-level visibility.
As a result, an authenticated user who is outside the relevant sharing group or who does not have visibility on the associated event could:
- Read the thread title and the content of the quoted post
- Submit a new post into the discussion thread
This constitutes both an information disclosure (reading restricted thread and post content) and an integrity issue (injecting content into a thread the user is not authorized to participate in).
Affected: <2.5.48
CVSS Details
- CVSS 4.0 Base Score: 5.3 (MEDIUM)
- CVSS 4.0 Vector: (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)
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