Get ahead
VMware offers training and certification to turbo-charge your progress.
Learn moreUnbounded persistent session allocation via repeated initialize requests
Description
The MCP Streamable HTTP server transport (WebFlux and WebMvc variants) does not place any limit on the number of sessions it retains, and by default does not require clients to be authenticated.
As a result, a remote attacker can cause the server to accumulate an unbounded number of sessions over time, gradually exhausting available memory and ultimately causing a Denial of Service that affects all legitimate clients.
Affected Spring Products and Versions
Spring AI:
- 2.0.0 - 2.0.0
Mitigation
Users of affected versions should upgrade to the corresponding fixed version.
| Fix version | Availability |
|---|---|
| 2.0.1 | OSS |
| 2.0.0.1 | Enterprise Support Only |
No further mitigation steps are necessary.
Credit
This issue was discovered internally.
History
- 2026-08-20: Initial vulnerability report published.
Reporting a vulnerability
To report a security vulnerability for a project within the Spring portfolio, see the Security Policy
Get support
Tanzu Spring offers support and binaries for OpenJDK™, Spring, and Apache Tomcat® in one simple subscription.
Learn moreUpcoming events
Check out all the upcoming events in the Spring community.
View all