high severity · published 2026-11-03
The MCP BoundSubject fingerprint uses the access method name instead of per-user identity for JWT/Bearer access. An attacker with a valid low-privilege token for the same access method and the victim's mcp-session-id can hijack the session and run MCP tools with the victim's roles and permissions.
Fixed in: 3.3.0
CVE: CVE-2026-121419
Source: NVD
You are affected if the installed version is older than 3.3.0. Check the version you have and update to 3.3.0 or later. The fixed version is verified against a vendor or advisory source.
FixLane has a reviewed fix procedure for this incident: a read-only check first, then the fix. Ask the Telegram bot, or connect an AI agent to the FixLane MCP server and call get_fix_prompt with incident id 670 and your operating system.