MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.6epss 0.2%
exploitation probability
0.2%top 85% of all CVEs
observed exploitation
nono source reports it
The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). From 1.23.0 until 1.27.2, default handlers installed by server.experimental.enable_tasks() for tasks/list, tasks/get, tasks/result, and tasks/cancel operate only on task identifiers without recording the session that created each task, allowing any connected client to enumerate, read results from, consume messages for, or cancel other clients' tasks. This issue is fixed in version 1.27.2.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
Affected products
modelcontextprotocol · python-sdkReferences
https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7https://github.com/modelcontextprotocol/python-sdk/pull/2720https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775