Summary
Null characters not escaped
Workarounds
Alternatively, null characters can be stripped out manually using e.g. arg.replace(/\u{0}/gu, "")
Impact
Anyone using Shescape to defend against shell injection may still be vulnerable against shell injection if the attacker manages to insert a null character into the payload. For example (on Windows):
const cp = require("child_process");
const shescape = require("shescape");
const nullChar = String.fromCharCode(0);
const payload = "foo\" && ls -al ${nullChar} && echo \"bar";
console.log(cp.execSync(`echo ${shescape.quote(payload)}`));
// foototal 3
// drwxr-xr-x 1 owner XXXXXX 0 Mar 13 18:44 .
// drwxr-xr-x 1 owner XXXXXX 0 Mar 13 00:09 ..
// drwxr-xr-x 1 owner XXXXXX 0 Mar 13 18:42 folder
// -rw-r--r-- 1 owner XXXXXX 0 Mar 13 18:42 file
CVE-2021-21384 has a CVSS score of 6.3 (High). The vector is requires local access, no privileges required, and user interaction required. 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 (1.1.3); 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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The problem has been patched in v1.1.3 which you can upgrade to now. No further changes are required.
Frequently Asked Questions
- What is CVE-2021-21384? CVE-2021-21384 is a high-severity security vulnerability in shescape (npm), affecting versions < 1.1.3. It is fixed in 1.1.3.
- How severe is CVE-2021-21384? CVE-2021-21384 has a CVSS score of 6.3 (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 shescape are affected by CVE-2021-21384? shescape (npm) versions < 1.1.3 is affected.
- Is there a fix for CVE-2021-21384? Yes. CVE-2021-21384 is fixed in 1.1.3. Upgrade to this version or later.
- Is CVE-2021-21384 exploitable, and should I be worried? Whether CVE-2021-21384 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-2021-21384 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-2021-21384? Upgrade
shescapeto 1.1.3 or later.