Summary
Regular Expression Denial of Service in websocket-extensions (NPM package)
Workarounds
There are no known work-arounds other than disabling any public-facing
WebSocket functionality you are operating.
References
Impact
The ReDoS flaw allows an attacker to exhaust the server's capacity to process
incoming requests by sending a WebSocket handshake request containing a header
of the following form:
Sec-WebSocket-Extensions: a; b="\c\c\c\c\c\c\c\c\c\c ...
That is, a header containing an unclosed string parameter value whose content is
a repeating two-byte sequence of a backslash and some other character. The
parser takes exponential time to reject this header as invalid, and this will
block the processing of any other work on the same thread. Thus if you are
running a single-threaded server, such a request can render your service
completely unavailable.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
CVE-2020-7662 has a CVSS score of 8.2 (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 (0.1.4); 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.
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Users should upgrade to version 0.1.4.
Frequently Asked Questions
- What is CVE-2020-7662? CVE-2020-7662 is a high-severity uncontrolled resource consumption vulnerability in websocket-extensions (npm), affecting versions < 0.1.4. It is fixed in 0.1.4. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- How severe is CVE-2020-7662? CVE-2020-7662 has a CVSS score of 8.2 (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.
- Which versions of websocket-extensions are affected by CVE-2020-7662? websocket-extensions (npm) versions < 0.1.4 is affected.
- Is there a fix for CVE-2020-7662? Yes. CVE-2020-7662 is fixed in 0.1.4. Upgrade to this version or later.
- Is CVE-2020-7662 exploitable, and should I be worried? Whether CVE-2020-7662 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-2020-7662 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-2020-7662? Upgrade
websocket-extensionsto 0.1.4 or later.