CVE-2026-2229 is a high-severity security vulnerability in undici (npm), affecting versions < 6.24.0. It is fixed in 6.24.0, 7.24.0.
Impact The undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the servermaxwindowbits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range servermaxwindowbits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination. The vulnerability exists because: The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15 The createInflateRaw() call is not wrapped in a try-catch block The resulting exception propagates up through the call stack and crashes the Node.js process Patches Has the problem been patched? What versions should users upgrade to? Workarounds Is there a way for users to fix or remediate the vulnerability without upgrading?
CVE-2026-2229 has a CVSS score of 7.5 (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 (6.24.0, 7.24.0). Upgrading removes the vulnerable code path.
npm
undici (< 6.24.0)undici (>= 7.0.0, < 7.24.0)undici → 6.24.0 (npm)undici → 7.24.0 (npm)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 instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-2229 is reachable in your applications. Explore open-source security for your team.
See if CVE-2026-2229 is reachable in your applications. Get a demo
Upgrade the following packages to resolve this vulnerability:
undici to 6.24.0 or laterundici to 7.24.0 or laterKodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-2229 is a high-severity security vulnerability in undici (npm), affecting versions < 6.24.0. It is fixed in 6.24.0, 7.24.0.
CVE-2026-2229 has a CVSS score of 7.5 (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.
undici (npm) versions < 6.24.0 is affected.
Yes. CVE-2026-2229 is fixed in 6.24.0, 7.24.0. Upgrade to this version or later.
Whether CVE-2026-2229 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
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.
undici to 6.24.0 or laterundici to 7.24.0 or later