Mattermost versions 10.4.x <= 10.4.2, 10.5.x <= 10.5.0, 9.11.x <= 9.11.9 fail to restrict domains the LLM can request to contact upstream which allows an authenticated user to exfiltrate data from an arbitrary server accessible to the victim via performing a prompt injection in the AI plugin's Jira tool.
Exploitability
AV:NAC:HPR:LUI:RScope
S:CImpact
C:LI:NA:N3/CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:N/A:NOther