Summary
Forge: TLS client crash when the server sends no certificate
The forge TLS client's check for a missing server certificate read the wrong property and never ran. A malicious TLS server, or an on-path attacker who removes the server's Certificate message, can make connection.process() throw a TypeError, which crashes applications that use the forge TLS client. Fixed in node-forge 1.4.1.
Details
After ServerHelloDone, tls.handleServerHelloDone() in lib/tls.js is meant to reject a server that sent no certificate with a fatal insufficient_security alert, after consulting the application's verify callback. The check tested c.serverCertificate, which is never set (the certificate is stored as c.session.serverCertificate), so it never ran. The client state machine allows ServerHelloDone directly after ServerHello, so the handshake continued to tls.createClientKeyExchange(), which reads c.session.serverCertificate.publicKey and throws a TypeError on the null certificate. The exception propagates out of connection.process() without calling the verify or error callbacks.
There is no authentication bypass: without a server certificate the client cannot build its RSA key exchange, so the handshake cannot complete.
The fix reads c.session.serverCertificate and always fails the handshake in that case, still calling verify so the application can customize the alert. Failing even when verify returns true is needed because the key exchange requires the certificate.
Workarounds
Catch exceptions thrown by connection.process() in the code that feeds it network data, and close the connection when one occurs.
Credits
Reported by @arpitjain099.
Proof of concept
Connect a forge TLS client (forge.tls.createConnection({server: false, ...})) to a server whose first flight contains ServerHello and ServerHelloDone but no Certificate message. For example, run a forge TLS server and remove the Certificate handshake message (type 11) from its first flight before passing it to the client's process().
On 1.4.0 the client's process() throws "TypeError: Cannot read properties of null (reading 'publicKey')", and the verify and error callbacks are not called. On 1.4.1 the client calls verify with insufficient_security and no certificates, calls error with "No server certificate provided. Not enough security.", sends a fatal alert and closes the connection.
Regression tests are in tests/unit/tls.js ("missing server certificate").
Impact
Applications that use the forge TLS client (forge.tls.createConnection with server: false) are affected. A malicious server the application connects to, or an on-path attacker who can modify the unauthenticated handshake, can make the client throw from connection.process(). Since process() is normally called from a socket data handler, the uncaught exception terminates a Node.js process. There is no confidentiality or integrity impact. Applications using Node.js's own TLS implementation are not affected.
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
CVE-2026-118778 has a CVSS score of 5.9 (Medium). 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 (1.4.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Fixed in node-forge 1.4.1. The TLS client fails the handshake with an insufficient_security alert when the server sends no certificate.
Frequently Asked Questions
- What is CVE-2026-118778? CVE-2026-118778 is a medium-severity null pointer dereference vulnerability in node-forge (npm), affecting versions <= 1.4.0. It is fixed in 1.4.1. The application dereferences a null pointer, causing a crash.
- How severe is CVE-2026-118778? CVE-2026-118778 has a CVSS score of 5.9 (Medium). 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.
- Which versions of node-forge are affected by CVE-2026-118778? node-forge (npm) versions <= 1.4.0 is affected.
- Is there a fix for CVE-2026-118778? Yes. CVE-2026-118778 is fixed in 1.4.1. Upgrade to this version or later.
- Is CVE-2026-118778 exploitable, and should I be worried? Whether CVE-2026-118778 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
- What actually determines whether CVE-2026-118778 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.
- How do I fix CVE-2026-118778? Upgrade
node-forgeto 1.4.1 or later.