CVE-2021-42740

Shell Quote vulnerability

CVSS

9.8

EPSS

4.3%

EPSS pct

90th

Exploited

No known

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.

Affected vendor

Shell Quote Project

Affected product

Shell Quote

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness type (CWE)

CWE-77 — Command Injection

Published

2021-10-21

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to confidentiality, high impact to integrity, high impact to availability.

Its EPSS score of 4.3% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 90% of all scored CVEs.

Check your external exposure to CVE-2021-42740

Confirm whether Shell Quote Project Shell Quote is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2021-42740.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2021-42740

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2021-42740 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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