Back to the CVE list
CVE-2026-116686

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

CVSS score

6.5

EPSS probability

—

Risk score

0.7

Published

2 h ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Patch status has not yet been verified

Resmî kaynaklarda yeterli kanıt bulunamadı. Bu sonuç “yama yok” anlamına gelmez.

Impact on My Inventory

Only the personal products you have added to your account are assessed; an organisation's inventory does not appear here.

Checking session…

Vulnerability description

DayBreach AI Explanation

Verified against sources

CVE-2026-116686: Model Context Protocol Python SDK Output Validation Vulnerability

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

The CVE-2026-116686 vulnerability in the Model Context Protocol Python SDK causes clients to fetch server-chosen $ref URLs.

Why does it matter?

This vulnerability allows malicious servers to read local files or create denial of service conditions on the client side.

What should be done?

  • Review and follow the vendor's official advisory
  • Update the affected versions
Chain of evidence and sources2 verified claims

Model Context Protocol Python SDK, sunucu tarafından seçilen $ref URL'lerini istemci bağlamında getirir.

S0 · daybreach-canonicalS1 · cvelist

Çözümleme işlemi olay döngüsünde zaman aşımı olmaksızın eş zamanlı çalışarak oturumları durdurabilir.

S0 · daybreach-canonicalS1 · cvelist
Show the technical text from the sources

The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. From 1.10.0 until 1.30.0 and 2.2.0, ClientSession, ClientSessionGroup, and Client tool calls validate server-declared outputSchema documents with jsonschema's default resolver, causing an unresolved $ref value to fetch an HTTP, HTTPS, or file URL from the client's network and filesystem context. A server can trigger blind requests or local-file reads and can stall every session in the process because resolution runs synchronously on the event loop without a timeout. This issue is fixed in versions 1.30.0 and 2.2.0.

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

CWE: CWE-918

This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-116686 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1modelcontextprotocolpython-sdk View
2pypimcp View
3pypimcp View
Total affected vendors: 2|Products: 3

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
6.5CVSS V31MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:HNVD
6.5CVSS V3_1MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:HCVE CNA
6.5CVSS 3.x—Vector not publishedGitHub Advisory
0.0CVSS 4.0—Vector not publishedGitHub Advisory

Patch and Remediation Guide

Solution & Remediation Advisory

Patch status unknown

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Until a patch is confirmed, follow the vendor advisory; do not read an unknown status as “no patch”.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-116686 is associated with the following CWEs:

CWE-918: Server-Side Request Forgery (SSRF)

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-116686 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsGerekmiyor
UserGerekiyor

Official Sources and Advisories

https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-rwrf-2pqf-9j8jvendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/pull/3394vendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/pull/3396vendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/commit/5ebdfed4060d8e5b11b8e2348f86bad4d1fb8836vendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/commit/6705402e246dc4eb1fcdf4d9902b78d3c9c36e1bvendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0vendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0vendor-advisoryhttps://github.com/advisories/GHSA-rwrf-2pqf-9j8jvendor-advisory

CVSS Vector Radar Chart

6.5 / 10
Attack VectorNetworkComplexityLowPrivilegesNoneUser Interact.RequiredConfidentialityLowIntegrityNoneAvailabilityHigh

Vulnerability Scoring Details

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone required
User Interaction—
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)None
Availability (Erişilebilirlik)High

Yama durumu bilinmiyor

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Follow the vendor

M
modelcontextprotocol logo
modelcontextprotocol
P
pypi logo
pypi

Weakness Type (CWE & CAPEC)

CWE-918

Similar Vulnerabilities

Get this vulnerability through the API

Affected products, version ranges, exploitation status and patch information in a single request, with a free key.

Get a free keyDocumentation
curl -H "x-api-key: $DAYBREACH_API_KEY" \
  "https://api.daybreach.dev/api/v1/intel/cves/CVE-2026-116686"
CVE-2026-116686 · Model Context Protocol Python SDK: Client…