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01 Record

CVE-2026-116686

Model Context Protocol Python SDK: Client fetched server-chosen $ref URLs while validating tool results against output schemas

MediumPUBLISHEDCNA: GitHub_M
CNA base score6.5 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
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02 Description

Model Context Protocol Python SDK: Client fetched server-chosen $ref URLs while validating tool results against output schemas

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.33% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 27.0% of scored records. A rank, not a probability.
NVD base score
6.5 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD analysis status
Deferred. NVD last modified this record on 2026-10-28.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-10-27 19:29Z1 DAY AGO
Last updated
2026-10-28 16:13Z17 HR AGO
Reserved
2026-10-26
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
Medium (CVSS 6.5)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weaknesses
  • CWE-918Server-Side Request Forgery (SSRF)Base
Data version
5.2
Document digest
8eae32ecd93e5c1309424b8667988033a6481808211e8a3b0b298a5d39bd367d

05 Affected products

VendorProductVersionsPlatforms
modelcontextprotocolpython-sdk>= 1.10.0, < 1.30.0, >= 2.0.0, < 2.2.0—

06 References