MediumVulnerabilityCVE-2026-116686updated 28 Oct 2026, 15:25 UTC
Model Context Protocol Python SDK: Client fetched server-chosen $ref URLs while validating tool results against output schemas
Fixed in mcp 2.2.0, mcp 1.30.0Official, 2 sources
| Severity | MediumCVSS 6.5 of 10 |
|---|---|
| Being exploited? | UnclearNo reports either way yet |
| Fix available? | Yesmcp 2.2.0, mcp 1.30.0 · since 27 Oct 2026 |
| How sure is this? | Official, 2 sourcesBacked by an official source |
Are you affected?
| Package / product | Affected versions | Fixed in |
|---|---|---|
| mcp · pip | >= 2.0.0, < 2.2.0 | 2.2.0 |
| mcp · pip | >= 1.10.0, < 1.30.0 | 1.30.0 |
Timeline
- 27 Oct 2026, 20:17 UTCPublicly disclosed
- 27 Oct 2026, 21:05 UTCReported by GitHub Advisory · GitHub Advisory
- 27 Oct 2026, 21:06 UTCPicked up by Zero Radar
- 28 Oct 2026, 15:25 UTCNVD reported on it · NVD
Sources 2 reports, oldest first
Official vendor, government CERT or advisory database
- CVE-2026-116686NVD · 27 Oct 2026, 20:17 UTC
- Model Context Protocol Python SDK: Client fetched server-chosen $ref URLs while validating tool results against output schemasGitHub Advisory · 27 Oct 2026, 21:05 UTC
Technical details
- ID
- CVE-2026-116686 · GHSA-rwrf-2pqf-9j8j
- CVSS
- 6.5 / 10
- Disclosed
- 27 Oct 2026, 20:17 UTC
- On Zero Radar
- 27 Oct 2026, 21:06 UTC (49 min after disclosure)
- Last change
- 28 Oct 2026, 15:25 UTC
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