CVE-2025-53365
MCP Python SDK has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service
EPSS 0.14%
Description
If a client deliberately triggers an exception after establishing a streamable HTTP session, this can lead to an uncaught ClosedResourceError on the server side, causing the server to crash and requiring a restart to restore service. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures. Thank you to Rich Harang for reporting this issue.
How to fix CVE-2025-53365
To remediate CVE-2025-53365, upgrade the affected package to a fixed version below.
- —upgrade to 1.10.0 or later
Is CVE-2025-53365 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 1.10.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 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 |