agent-router: MCP session resume does not verify the embedded anti-hijacking subject; default Helm seed makes session IDs forgeable

影響: go:github.com/envoyproxy/ai-gateway >= 0.4.0-rc1, < 1.2.0-rc1 → 1.2.0-rc1

The MCP proxy's client-facing session ID embeds the authenticated caller's subject (JWT sub claim) specifically as an anti-hijacking discriminator — matching the Model Context Protocol specification's documented session-hijacking guidance (https://modelcontextprotocol.io/specification/2025-06-18/basic/security_best_practices#session-hijacking). However, the session-resume path never checks that discriminator against the current caller's identity, so any client that obtains a session ID…

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On 10/20/2026, 01:53 AM, GitHub Advisory Database published "agent-router: MCP session resume does not verify the embedded anti-hijacking subject; default Helm seed makes session IDs forgeable" (type: Advisory). Severity is "Medium" (medium). Related technologies: Go, GitHub.