MediumCVE-2026-111769

    @modelcontextprotocol SDK: Exposure of Sensitive Information to an Unauthorized Actor (CVE-2026-111769)

    Published Last modified Sources: CVE.org, OSV, Hersteller

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    What is affected, what to do

    The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. Prior to 1.32.0 in @modelcontextprotocol/sdk and from 2.0.0 until 2.3.0 in @modelcontextprotocol/client, the HTTP client transports and OAuth client requests followed redirects to a different origin while retaining custom request headers and, for HTTP 307 or 308 responses, request bodies.

    Update Modelcontextprotocol Typescript-sdk to version 1.32.0, @modelcontextprotocol SDK to version 1.32.0.

    Affected
    • Modelcontextprotocol Typescript-sdk lt *..1.32.0
    • @modelcontextprotocol SDK lt *..1.32.0
    • @modelcontextprotocol Client gte 2.0.0, < 2.3.0..*
    Fixed in
    • Modelcontextprotocol Typescript-sdk 1.32.0
    • @modelcontextprotocol SDK 1.32.0

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    6.5

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    6.5

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: CVE.org, OSV, Hersteller

    —

    EPSS score

    No value is available for this vulnerability.

    Show all metrics
    Severity
    Medium
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    62.50 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    6.5 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    6.5
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-200

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. Prior to 1.32.0 in @modelcontextprotocol/sdk and from 2.0.0 until 2.3.0 in @modelcontextprotocol/client, the HTTP client transports and OAuth client requests followed redirects to a different origin while retaining custom request headers and, for HTTP 307 or 308 responses, request bodies. The affected surfaces are StreamableHTTPClientTransport, SSEClientTransport, and OAuth client functions such as auth(). The trigger is an HTTP redirect to another origin. Custom headers and mcp-session-id can be re-sent to the redirected origin. HTTP 307 and 308 redirects can also re-send the request body. OAuth request bodies can contain refresh_token and client_secret values. Current runtimes already strip the Authorization header across origins. stdio clients do not use the affected HTTP path. A malicious or compromised MCP or authorization server could therefore receive API keys, session identifiers, OAuth refresh tokens, or OAuth client secrets. Restoring unrestricted redirect following after upgrading restores the exposure. This issue is fixed in @modelcontextprotocol/sdk 1.32.0 and @modelcontextprotocol/client 2.3.0.

    Source: cvelistv5, NVD (NIST), CVE.org (MITRE), OSV (Open Source Vulnerabilities), GitHub Security Advisories

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    @modelcontextprotocolclient
    • ≥ 2.0.0, < 2.3.0
    • —
    @modelcontextprotocolsdk
    • < 1.32.0
    • 1.32.0
    modelcontextprotocoltypescript-sdk
    • < 1.32.0
    • 1.32.0
    npm@modelcontextprotocol/client
    • >= 2.0.0, < 2.3.0
    • 2.0.0
    • 2.3.0
    • 2.3.0
    npm@modelcontextprotocol/sdk
    • —
    • < 1.32.0
    • 1.32.0
    • 1.32.0

    Vendors and products

    Weakness classes (CWE)

    • CWE-200Exposure of Sensitive Information to an Unauthorized Actor

      Class

      The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

      Entry at MITRE CWE-200

    References & sources

    • github.commodelcontextprotocol/typescript-sdk/security/advisories/GHSA-6p…web, x_refsource_CONFIRM
    • github.commodelcontextprotocol/typescript-sdk/pull/2901web, x_refsource_MISC
    • github.commodelcontextprotocol/typescript-sdk/pull/2902web, x_refsource_MISC
    • github.commodelcontextprotocol/typescript-sdk/commit/30bfe5139f4b0825c90c…web, x_refsource_MISC
    • github.commodelcontextprotocol/typescript-sdk/commit/433eb413dc305ebeb93b…web, x_refsource_MISC
    • github.commodelcontextprotocol/typescript-sdkpackage
    • github.commodelcontextprotocol/typescript-sdk/releases/tag/1.32.0x_refsource_MISC
    • github.commodelcontextprotocol/typescript-sdk/releases/tag/@modelcontextp…x_refsource_MISC

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. ReceivedGitHub

      CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

      Weakness type: CWE-200

      Description added or changed

      Show 11 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. Prior to 1.32.0 in @modelcontextprotocol/sdk and from 2.0.0 until 2.3.0 in @modelcontextprotocol/client, the HTTP client transports and OAuth client requests followed redirects to a different origin while retaining custom request headers and, for HTTP 307 or 308 responses, request bodies. The affected surfaces are StreamableHTTPClientTransport, SSEClientTransport, and OAuth client functions such as auth(). The trigger is an HTTP redirect to another origin. Custom headers and mcp-session-id can be re-sent to the redirected origin. HTTP 307 and 308 redirects can also re-send the request body. OAuth request bodies can contain refresh_token and client_secret values. Current runtimes already strip the Authorization header across origins. stdio clients do not use the affected HTTP path. A malicious or compromised MCP or authorization server could therefore receive API keys, session identifiers, OAuth refresh tokens, or OAuth client secrets. Restoring unrestricted redirect following after upgrading restores the exposure. This issue is fixed in @modelcontextprotocol/sdk 1.32.0 and @modelcontextprotocol/client 2.3.0.
      CVSSadded
      —
      AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
      Weakness type (CWE)added
      —
      CWE-200
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/111xxx/CVE-2026-111769.json">CVE-2026-111769</a>
      Referenceadded
      —
      https://github.com/modelcontextprotocol/typescript-sdk/commit/30bfe5139f4b0825c90cd725f9a7e3f9af5e120d
      Referenceadded
      —
      https://github.com/modelcontextprotocol/typescript-sdk/commit/433eb413dc305ebeb93b8ebcde0095a8fc0d5fa0
      Referenceadded
      —
      https://github.com/modelcontextprotocol/typescript-sdk/pull/2901
      Referenceadded
      —
      https://github.com/modelcontextprotocol/typescript-sdk/pull/2902
      Referenceadded
      —
      https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server@2.3.0
      Referenceadded
      —
      https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/1.32.0
      Referenceadded
      —
      https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6prh-2h8m-c8cw

      Source identifier: security-advisories@github.com

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