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MCP TypeScript SDK UriTemplate Exploded Array Pattern ReDoS

Type: advisorySource: Official CVE List1 source record

Anthropic's MCP TypeScript SDK versions up to and including 1.25.1 contain a regular expression denial of service (ReDoS) vulnerability in the UriTemplate class when processing RFC 6570 exploded array patterns. The dynamically generated regular expression used during URI matching contains nested quantifiers that can trigger catastrophic backtracking on specially crafted inputs, resulting in excessive CPU consumption. An attacker can exploit this by supplying a malicious URI that causes the Node.js process to become unresponsive, leading to a denial of service.

Announced Source revision 1
Original source ↗

CVE-2026-0621

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-0621

MCP TypeScript SDK

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://github.com/modelcontextprotocol/typescript-sdk",
    "vendor": "Anthropic",
    "product": "MCP TypeScript SDK",
    "versions": [
      {
        "status": "affected",
        "version": "0",
        "versionType": "semver",
        "lessThanOrEqual": "1.25.1"
      }
    ],
    "packageURL": "pkg:npm/%40modelcontextprotocol/sdk",
    "defaultStatus": "unaffected"
  }
]
Related CVEs
CVE-2026-0621

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#12654 · Revision 1
Added to Heist Feed
Publisher date
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