CVE-2021-42740

The shell-quote package before 1.7.3 for Node.js allows command injection. An attacker can inject unescaped shell metacharacters through a regex designed to support Windows drive letters. If the output of this package is passed to a real shell as a quoted argument to a command with exec(), an attacker can inject arbitrary commands. This is because the Windows drive letter regex character class is {A-z] instead of the correct {A-Za-z]. Several shell metacharacters exist in the space between capital letter Z and lower case letter a, such as the backtick character.

Published: 2021-10-21 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-42740 is rated High Risk (66/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 4.34%). High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-42740

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 9.04% 4.34% -4.70%
2 2026-03-06 5.37% 9.04% +3.68%
3 2026-03-04 — 5.37% —

Full EPSS history (53 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-42740

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-42740

GitHub Security Advisory for CVE-2021-42740

GHSA-g4rg-993r-mgx7 · Severity: critical · Ecosystem: npm — Improper Neutralization of Special Elements used in a Command in Shell-quote

OS Trackers for CVE-2021-42740

vendor priority summary link
debian not yet assigned CVE-2021-42740 not yet assigned priority: Debian including 1 source packages (node-shell-quote), 4 status rows across 4 suites (bookworm, forky, sid, trixie): resolved 4. https://security-tracker.debian.org/tracker/CVE-2021-42740
suse critical — https://www.suse.com/security/cve/CVE-2021-42740/
ubuntu medium CVE-2021-42740 medium priority: Ubuntu including 1 source packages (node-shell-quote), 15 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 8, DNE 3, ignored 2, needed 1, needs-triage 1. https://ubuntu.com/security/CVE-2021-42740

Affected software / configurations for CVE-2021-42740

Vendor Product Version Raw CPE
shell-quote_project shell-quote < 1.7.3 cpe:2.3:a:shell-quote_project:shell-quote:*:*:*:*:*:node.js:*:*

References for CVE-2021-42740

cvelogic Threat Intelligence