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.
CVE ID: CVE-2025-31363
CVSS Base Severity: LOW
CVSS Base Score: 3.0
CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:N/A:N
Vendor: Mattermost
Product: Mattermost
EPSS Score: 0.03% (probability of being exploited)
EPSS Percentile: 5.88% (scored less or equal to compared to others)
EPSS Date: 2025-04-18 (when was this score calculated)