CVE-2026-103921

GraphQL Tools: TLS Certificate Validation Disabled in Legacy GraphQL WebSocket Executor

Workarounds

• Prefer the modern graphql-ws / SubscriptionProtocol.WS path where possible.
• Until upgraded, avoid sending secrets over legacy WSS connections, or terminate TLS at a trusted proxy and use ws:// only on trusted networks.
• Supply a custom webSocketImpl that enforces certificate validation.

buildWSLegacyExecutor() in @graphql-tools/executor-legacy-ws previously hardcoded rejectUnauthorized: false when creating WebSocket connections over WSS. This disabled TLS certificate validation, allowing a network-positioned attacker to perform a Man-in-the-Middle (MITM) attack against applications that use this executor with a wss:// endpoint. Credentials passed via connectionParams or headers could be intercepted, and subscription data could be tampered with.

Who is impacted: Applications using @graphql-tools/executor-legacy-ws (directly or via @graphql-tools/url-loader with SubscriptionProtocol.LEGACY_WS) to connect to a wss:// endpoint from Node.js while sending authentication material over the connection.

Browser WebSocket clients are unaffected by this option (browsers always validate certificates).

CVE-2026-103921 has a CVSS score of 7.4 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.1.35); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

Upgrade to @graphql-tools/[email protected] or later (and @graphql-tools/[email protected] or later if you use the loader). TLS certificate validation is enabled by default. Callers that intentionally use self-signed certificates in trusted environments can opt out with rejectUnauthorized: false.

1. What is CVE-2026-103921? CVE-2026-103921 is a high-severity security vulnerability in @graphql-tools/executor-legacy-ws (npm), affecting versions <= 1.1.34. It is fixed in 1.1.35.
2. How severe is CVE-2026-103921? CVE-2026-103921 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @graphql-tools/executor-legacy-ws are affected by CVE-2026-103921? @graphql-tools/executor-legacy-ws (npm) versions <= 1.1.34 is affected.
4. Is there a fix for CVE-2026-103921? Yes. CVE-2026-103921 is fixed in 1.1.35. Upgrade to this version or later.
5. Is CVE-2026-103921 exploitable, and should I be worried? Whether CVE-2026-103921 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-103921 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-103921? Upgrade @graphql-tools/executor-legacy-ws to 1.1.35 or later.

Other vulnerabilities in @graphql-tools/executor-legacy-ws