Is CVE-2026-59950 in the CISA KEV catalog?

No. CVE-2026-59950 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-59950?

CVE-2026-59950 has a CVSS v3 base score of 8.1 (HIGH).

What is the EPSS score for CVE-2026-59950?

CVE-2026-59950 has an EPSS score of 0.15% (5th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-59950?

Upgrade mcp python sdk to 1.28.1 or later.

CVE & CISA-KEV Catalog

CVE-2026-59950

HIGH

8.1

CVSS v3

NVD

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.

CWE-346 CWE-1385

How to fix

Remediation Available

mcp python sdkNVD

Affected:< 1.28.1Fixed in:1.28.1CVE-2026-59950derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Exploit Intelligence

0.15%probability of exploitation in 30 days

5thpercentile

Low risk: more likely to be exploited than 5% of all known CVEs.

References

Patch2

Vendor Advisory1

github.com

Release Notes1

github.com

Related Vulnerabilities

Other CWE-346 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2009-1185	High	7.2	82%	-	Fix
CVE-2025-34291	High	8.8	79%	KEV	-
CVE-2020-16952	High	8.6	71%	-	-
CVE-2023-29711	Critical	9.8	70%	-	-
CVE-2015-4495	High	8.8	70%	KEV	Fix
CVE-2024-23898	High	8.8	67%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-17.