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@modelcontextprotocol/server-legacy

Open actionable advisories and recorded vendor fixes. This public package view has no inventory attached and cannot establish whether your deployment is affected. A vendor fix never resolves your finding; verify your installed version and the source guidance.

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1 actionable advisory, newest first. Withdrawn advisories and news are excluded. Coverage is partial.

  1. Medium, CVSS 6.8npmAmendedPublished

    MCP TypeScript SDK: Server bearer authentication accepted tokens issued for another service

    CVE-2026-111771 · GHSA-rvq5-wwqv-78pq

    Affected
    • npm @modelcontextprotocol/server-legacy >= 2.0.0, < 2.3.1
    Fixed in
    2.3.1· Vendor fix available
    Issue
    In affected versions, the SDK's server-side bearer authentication had no way to check that a token was issued for your server (its audience). Where one authorization server issues tokens for several services, a valid token for another service was also accepted by your MCP server. Am I affected? Yes, if your HTTP server uses requireBearerAuth() or verifyBearerToken(), its authorization server also issues tokens for other services, and your verifyAccessToken() does not check the token's audience (aud) itself. Affected versions: - @modelcontextprotocol/sdk 1.6.0 through 1.31.0 - @modelcontextprotocol/server 2.0.0 through 2.2.0 - @modelcontextprotocol/express 2.0.0 through 2.0.1 - @modelcontextprotocol/server-legacy 2.0.0 through 2.3.0 Fix Upgrade to: - 1.x: @modelcontextprotocol/sdk 1.32.0 or later - 2.x: @modelcontextprotocol/server 2.3.0 or later, together with @modelcontextprotocol/express 2.0.2 or later if you use it - @modelcontextprotocol/server-legacy 2.3.1 or later…

    Recommended action: Upgrade to 2.3.1 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.

    Sources:github.com (1)osv.dev (2)Source checked Evidence →