EUVD-2026-44797Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
Attacker must be a connected client (PR:L) reaching the server over the network at low complexity (AV:N/AC:L); reading other tasks' results gives C:H while cancel/consume yields only I:L/A:L, scope unchanged.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
Lifecycle Timeline
4DescriptionCVE.org
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.
Articles & Coverage 1
AnalysisAI
Missing authorization in the MCP Python SDK (the mcp PyPI package) versions 1.23.0 through 1.27.1 lets any authenticated client of a multi-client server enumerate, read the results of, consume messages from, or cancel tasks belonging to other clients. The default handlers wired up by server.experimental.enable_tasks() for tasks/list, tasks/get, tasks/result, and tasks/cancel key solely on the task identifier and never bind a task to the session that created it. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a stateful MCP server that has called `server.experimental.enable_tasks()` and serves more than one client/session concurrently, with the attacker already an authenticated connected client (PR:L). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L, base 7.6) describes a network-reachable, low-complexity attack requiring only that the attacker already be a connected client (PR:L), yielding high confidentiality impact (reading other clients' task results) with lower integrity/availability impact (cancelling tasks, consuming their messages). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker connects to a shared, task-enabled MCP server as a legitimate client, then issues tasks/list to enumerate task IDs created by other sessions and follows up with tasks/get and tasks/result to read those tasks' outputs, or tasks/cancel to abort a victim's in-flight work. Because exploitation only requires being a connected client on the network (AV:N/AC:L/PR:L) with no user interaction, it is straightforward wherever multiple clients share one stateful server. … |
| Remediation | Vendor-released patch: upgrade the `mcp` package to version 1.27.2 or later, which binds generated task IDs to the creating session so the default handlers reject cross-session access (see the advisory GHSA-hvrp-rf83-w775 and release https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2, fix in PR https://github.com/modelcontextprotocol/python-sdk/pull/2720 and commit 62137874ff26dd74d2fea80ff528a7fd9ca7a5e7). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all systems and services using the mcp PyPI package and document their current versions. …
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External POC / Exploit Code
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