How severe is CVE-2026-59950?

CVE-2026-59950 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-59950 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-59950?

CVE-2026-59950 affects Lfprojects Mcp Python Sdk. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59950?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-59950 published?

CVE-2026-59950 was published on 2026-07-15 and last updated on 2026-07-17.

CVE-2026-59950

CVE-2026-59950 is a high-severity vulnerability in Lfprojects Mcp Python Sdk with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-346.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v4: 7.6
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-346
Affected product: Lfprojects Mcp Python Sdk
Published: 2026-07-15
Last modified: 2026-07-17

Description

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.28.1, the deprecated mcp.server.websocket.websocket_server transport accepted WebSocket handshakes without applying Host or Origin header validation, leaving no SDK-level way to restrict which origins could connect to applications that exposed that transport. This issue is fixed in version 1.28.1.

Frequently asked questions

What is CVE-2026-59950?: The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.28.1, the deprecated mcp.server.websocket.websocket_server transport accepted WebSocket handshakes without applying Host or Origin header validation, leaving no SDK-level way to restrict which origins could connect to applications that exposed that transport. This issue is fixed in version 1.28.1.
How severe is CVE-2026-59950?: CVE-2026-59950 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-59950 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59950?: CVE-2026-59950 affects Lfprojects Mcp Python Sdk. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59950?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-59950 published?: CVE-2026-59950 was published on 2026-07-15 and last updated on 2026-07-17.

References

Affected products (1)

cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:*

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