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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.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:8fa379a4ef2806e1e0a665c38d3b3d662d478f737bb8cbb93983a63e56efa498
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
1

Preserved source conflicts

No provider value was silently selected as the winner.

cwe · 2 assertions

{"cweId":"CWE-346","description":"CWE-346: Origin Validation Error","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/problemTypes/0/descriptions/0

{"cweId":"CWE-1385","description":"CWE-1385: Missing Origin Validation in WebSockets","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/problemTypes/1/descriptions/0

Affected products and versions

1 source assertion
{"product":"python-sdk","vendor":"modelcontextprotocol","versions":[{"status":"affected","version":"< 1.28.1"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":7.6,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"PASSIVE","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH"},"metric_type":"cvssV4_0"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/metrics/0/cvssV4_0

CWE assertions

2 source assertions
{"cweId":"CWE-346","description":"CWE-346: Origin Validation Error","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/problemTypes/0/descriptions/0
{"cweId":"CWE-1385","description":"CWE-1385: Missing Origin Validation in WebSockets","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/problemTypes/1/descriptions/0

Source references

4 source assertions
{"name":"https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/references/2
{"name":"https://github.com/modelcontextprotocol/python-sdk/pull/2992","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/python-sdk/pull/2992"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/references/1
{"name":"https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/references/3
{"name":"https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w","tags":["x_refsource_CONFIRM"],"url":"https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:ec34bea5a639dc7a68271adf853aa6930e905da7a9625f539ce21a463a516068 · sha256:1d54dce3620adc8c… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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