CVE-2026-59279 Security Details

CVE ID

CVE-2026-59279

CWE

CWE-770

CVE 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 versions: Spring AI: 2.0.0

Published

Aug 21, 2026

CVSS Score & Severity

8.7High

CVSS Vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

EPSS Score

0.549%

Malware

malware

KEV Status

Not in KEV Catalog: No known exploits

Vulnerable Methods

io/modelcontextprotocol/server/transport/WebFluxStreamableServerTransportProvider.handlePost(Lorg/springframework/web/reactive/function/server/ServerRequest;)Lreactor/core/publisher/Mono;

JVMVulnerable params: 0

io/modelcontextprotocol/server/transport/WebMvcStreamableServerTransportProvider.handlePost(Lorg/springframework/web/servlet/function/ServerRequest;)Lorg/springframework/web/servlet/function/ServerResponse;

JVMVulnerable params: 0

org/springframework/ai/mcp/server/webflux/transport/WebFluxStreamableServerTransportProvider.handlePost(Lorg/springframework/web/reactive/function/server/ServerRequest;)Lreactor/core/publisher/Mono;

JVMVulnerable params: 0

org/springframework/ai/mcp/server/webmvc/transport/WebMvcStreamableServerTransportProvider.handlePost(Lorg/springframework/web/servlet/function/ServerRequest;)Lorg/springframework/web/servlet/function/ServerResponse;

JVMVulnerable params: 0

Affected Ecosystems

affected

Source

National Vulnerability Database

References

spring.ioPROJECT