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Advisory record · GHSA-j975-95f5-7wqh

MCP Python SDK has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service

CVSS 8.7 HighEPSS 0.0042 · 36th percentile

Published by the GitHub Advisory Database at 4 Jul 2025, 22:06 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
mcpPyPI<1.10.01.10.0
Identifiers
GHSA-j975-95f5-7wqh · CVE-2025-53365 · PYSEC-2026-1618
Weakness (CWE)
CWE-248
Tags
Published
4 Jul 2025
Updated
16 Jul 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The mcp Python SDK, versions before 1.10.0, is vulnerable to a denial of service in its streamable HTTP transport. A client that deliberately triggers an exception after establishing a streamable HTTP session can cause an uncaught error that crashes the server, which then needs a restart to restore service. Upgrade mcp to version 1.10.0 or later; the source gives few details on deployment-specific impact.

Written 5 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.7 High 4.0 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 CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0042, the 36th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:42 UTC First seen by agentprime
  2. 31 Oct 2026, 14:42 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.