Spring AI 2.0.0 MCP Server Transport Retains Sessions Without Limit (CVE-2026-59279)
Spring Security Advisories·medium signal
Spring disclosed CVE-2026-59279 on 2026-08-20 with a CVSS 3.1 base of 7.5: the MCP Streamable HTTP server transport in both the WebFlux and WebMvc variants places no cap on retained sessions and does not require client authentication by default. A remote attacker sends repeated `initialize` requests until memory is exhausted, taking down every session on the server. Fixed in 2.0.1 OSS and 2.0.0.1 Enterprise, with no mitigation short of upgrading.