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CVE-2026-116684

Model Context Protocol Python SDK: Server bearer-token authentication accepts tokens issued for a different resource server

CVSS score

6.8

EPSS probability

—

Risk score

0.7

Published

3 h ago

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

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Vulnerability description

DayBreach AI Explanation

Verified against sources

CVE-2026-116684: Model Context Protocol Python SDK Authentication Vulnerability

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

Model Context Protocol Python SDK versions from 1.10.0 to before 1.30.0 and version 2.2.0 allow server-side bearer authentication to accept valid tokens issued for a different resource server. This resource-confusion flaw lets a token holder authenticate to the wrong MCP server.

Why does it matter?

Unauthorized users can authenticate to an incorrect MCP server using a valid token issued for another service, enabling unintended access to sensitive resources.

What should be done?

  • Update Model Context Protocol Python SDK packages
  • Follow the vendor advisory for patch guidance
  • Verify token verification implementation
Chain of evidence and sources2 verified claims

Model Context Protocol Python SDK, 1.10.0 ile 1.30.0 arası ve 2.2.0 sürümlerinde bearer-token kimlik doğrulamasında kaynak karışıklığı zafiyeti barındırmaktadır.

S0 · daybreach-canonicalS1 · cvelist

Yetkilendirme sunucusu birden fazla kaynağa hizmet verdiğinde ve aud doğrulanmadığında, farklı bir servis için verilen token kabul edilir.

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, server-side bearer authentication configured through AuthSettings with token_verifier accepts a valid token issued for another service when the authorization server serves multiple resources and the TokenVerifier does not independently validate the aud audience. This resource-confusion flaw lets a token holder authenticate to the wrong MCP server and exercise that token's resulting access. This issue is fixed in versions 1.30.0 and 2.2.0.

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

CWE: CWE-863

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-2026-116684 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
6.8CVSS V3_1MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:NCVE CNA
6.8CVSS V31MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:NNVD
6.8CVSS 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-2026-116684 is associated with the following CWEs:

CWE-863: Common Weakness Enumeration Entry CWE-863

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-2026-116684 weaknesses.

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

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsLow
UserGerekmiyor

Official Sources and Advisories

https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-w4fh-qvv9-3v23vendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/pull/3447vendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/pull/3451vendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/commit/0c9136841ff092987a20700ff9c2c9789bda2f40vendor-advisoryhttps://github.com/modelcontextprotocol/python-sdk/commit/8c2fa6eabacde869d75568e33b9d466b58c2f512vendor-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-w4fh-qvv9-3v23vendor-advisory

CVSS Vector Radar Chart

6.8 / 10
Attack VectorNetworkComplexityHighPrivilegesLowUser Interact.NoneConfidentialityHighIntegrityNoneAvailabilityNone

Vulnerability Scoring Details

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredLow privileges
User InteractionNone required
Confidentiality (Gizlilik)High
Integrity (Bütünlük)None
Availability (Erişilebilirlik)None

Yama durumu bilinmiyor

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

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Weakness Type (CWE & CAPEC)

CWE-863

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CVE-2026-116684 · Model Context Protocol Python SDK: Server…