Is mcp affected by CVE-2026-33946?

RubyGems mcp is affected in <0.9.2.

Is CVE-2026-33946 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.5%.

high

CVE-2026-33946

Q: Is CVE-2026-33946 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.5%.

RubyGems · mcp

Summary

MCP Ruby SDK: Insufficient Session Binding Allows SSE Stream Hijacking via Session ID Replay

Severity: high
EPSS: 0.5% (p37)
Also known as: GHSA-qvqr-5cv7-wh35
Published: 2026-03-27

References

https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-qvqr-5cv7-wh35
https://nvd.nist.gov/vuln/detail/CVE-2026-33946
https://github.com/modelcontextprotocol/ruby-sdk/commit/db40143402d65b4fb6923cec42d2d72cb89b3874

Related advisories

CVE-2025-66416 — high · PyPI/mcp
CVE-2025-53366 — high · PyPI/mcp
CVE-2025-53365 — high · PyPI/mcp

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.