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Response snapshot Oct 28, 2026, 16:36 UTC

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VulnerabilityCVE-2026-59176

Functype is a family of TypeScript functional programming libraries.

Functype is a family of TypeScript functional programming libraries. Prior to 1.4.4, the set_functype_version MCP tool in functype-mcp-server accepts an unconstrained version string using only z.string() validation in packages/mcp-server/src/index.

At a glance

Exploited
Not known
Severity
7.8 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-59176 (opens a new tab)

What happened

Functype is a family of TypeScript functional programming libraries. Prior to 1.4.4, the set_functype_version MCP tool in functype-mcp-server accepts an unconstrained version string using only z.string() validation in packages/mcp-server/src/index.ts and interpolates it into functype@<version> for pnpm add.

Package-alias syntaxes such as file:, npm:, URLs, or paths can cause an arbitrary local or remote package to be installed as functype. Immediately afterward, initDocsData(true) in packages/mcp-server/src/lib/docs/data.ts resolves functype/cli and dynamically imports the newly installed module, executing attacker-controlled JavaScript with the MCP server process's privileges.

Any MCP client able to send a tools/call request invoking the tool can exploit the flaw; the tool is enabled by default without authentication in stdio mode. A connected AI assistant susceptible to indirect prompt injection can also be induced to invoke it from a malicious document or web page. In non-default TRANSPORT_TYPE=httpStream deployments, a network-accessible attacker does not require local access.

Successful execution can read process secrets, modify files, or terminate the server. This issue is fixed in version 1.4.4.

Scores and how they were measured

CVSS base severity

7.8

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Sources

  1. Primary source

    NVD CVE-2026-59176 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 28). Functype is a family of TypeScript functional programming libraries. (CVE-2026-59176). https://kevwire.com/record/CVE-2026-59176

MLA

"Functype is a family of TypeScript functional programming libraries. (CVE-2026-59176)." KEVWire, 28 Oct. 2026, kevwire.com/record/CVE-2026-59176.

Chicago

KEVWire. "Functype is a family of TypeScript functional programming libraries. (CVE-2026-59176)." Last modified October 28, 2026. https://kevwire.com/record/CVE-2026-59176.

Evidence summary (plain text)

Functype is a family of TypeScript functional programming libraries. (Oct 28, 2026).
Functype is a family of TypeScript functional programming libraries. Prior to 1.4.4, the set_functype_version MCP tool in functype-mcp-server accepts an unconstrained version string using only z.string() validation in packages/mcp-server/src/index.ts and interpolates it into functype@<version> for pnpm add. Package-alias syntaxes such as file:, npm:, URLs, or paths can cause an arbitrary local or remote package to be installed as functype.
CVSS 7.8 (version 3.1; evidence as of Oct 28, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-59176).
Sources:
NVD CVE-2026-59176: https://nvd.nist.gov/vuln/detail/CVE-2026-59176
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-28T14:31:18.089Z&lastModEndDate=2026-10-28T16:10:57.523Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-28T13:56:05.512Z&lastModEndDate=2026-10-28T15:30:58.735Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-28T13:20:57.566Z&lastModEndDate=2026-10-28T14:55:56.021Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-28T12:50:59.682Z&lastModEndDate=2026-10-28T14:20:56.266Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-59176.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 28, 2026, 16:10 UTC. Ingestion is not an independent editorial investigation.

NVD status: Deferred. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

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Record details

Record detail