CVE-2021-21384 Vulnerability Analysis & Exploit Details

CVE-2021-21384
Vulnerability Scoring

6.3
/10
High Risk

If left unpatched, CVE-2021-21384 could lead to major system disruptions or data loss.

Attack Complexity Details

  • Attack Complexity: High
    Exploits require significant effort and special conditions.
  • Attack Vector: Local
    Vulnerability requires local system access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Changed
    Successful exploitation can impact components beyond the vulnerable component.
  • User Interaction: Required
    User interaction is necessary for successful exploitation.

CVE-2021-21384 Details

Status: Modified

Last updated: 🕠 21 Nov 2024, 05:48 UTC
Originally published on: 🕛 19 Mar 2021, 00:15 UTC

Time between publication and last update: 1343 days

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2021-21384 Vulnerability Summary

CVE-2021-21384: shescape is a simple shell escape package for JavaScript. In shescape before version 1.1.3, anyone using _Shescape_ to defend against shell injection may still be vulnerable against shell injection if the attacker manages to insert a into the payload. For an example see the referenced GitHub Security Advisory. The problem has been patched in version 1.1.3. No further changes are required.

Assessing the Risk of CVE-2021-21384

Access Complexity Graph

The exploitability of CVE-2021-21384 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2021-21384

CVE-2021-21384 presents a challenge to exploit due to its high attack complexity, but the absence of privilege requirements still makes it a viable target for skilled attackers. A thorough security review is advised.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2021-21384, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2021-21384, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: Low
    CVE-2021-21384 could lead to minor leaks of non-critical information without major privacy breaches.
  • Integrity: High
    CVE-2021-21384 could allow unauthorized modifications to data, potentially affecting system reliability and trust.
  • Availability: None
    CVE-2021-21384 does not impact system availability.

Exploit Prediction Scoring System (EPSS)

The EPSS score estimates the probability that this vulnerability will be exploited in the near future.

EPSS Score: 0.081% (probability of exploit)

EPSS Percentile: 37.56% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 62.44% of others.

CVE-2021-21384 References

External References

CWE Common Weakness Enumeration

CWE-88

CAPEC Common Attack Pattern Enumeration and Classification

  • Parameter Injection CAPEC-137 An adversary manipulates the content of request parameters for the purpose of undermining the security of the target. Some parameter encodings use text characters as separators. For example, parameters in a HTTP GET message are encoded as name-value pairs separated by an ampersand (&). If an attacker can supply text strings that are used to fill in these parameters, then they can inject special characters used in the encoding scheme to add or modify parameters. For example, if user input is fed directly into an HTTP GET request and the user provides the value "myInput&new_param=myValue", then the input parameter is set to myInput, but a new parameter (new_param) is also added with a value of myValue. This can significantly change the meaning of the query that is processed by the server. Any encoding scheme where parameters are identified and separated by text characters is potentially vulnerable to this attack - the HTTP GET encoding used above is just one example.
  • Flash Parameter Injection CAPEC-174 An adversary takes advantage of improper data validation to inject malicious global parameters into a Flash file embedded within an HTML document. Flash files can leverage user-submitted data to configure the Flash document and access the embedding HTML document.
  • Using Meta-characters in E-mail Headers to Inject Malicious Payloads CAPEC-41 This type of attack involves an attacker leveraging meta-characters in email headers to inject improper behavior into email programs. Email software has become increasingly sophisticated and feature-rich. In addition, email applications are ubiquitous and connected directly to the Web making them ideal targets to launch and propagate attacks. As the user demand for new functionality in email applications grows, they become more like browsers with complex rendering and plug in routines. As more email functionality is included and abstracted from the user, this creates opportunities for attackers. Virtually all email applications do not list email header information by default, however the email header contains valuable attacker vectors for the attacker to exploit particularly if the behavior of the email client application is known. Meta-characters are hidden from the user, but can contain scripts, enumerations, probes, and other attacks against the user's system.
  • HTTP Parameter Pollution (HPP) CAPEC-460 An adversary adds duplicate HTTP GET/POST parameters by injecting query string delimiters. Via HPP it may be possible to override existing hardcoded HTTP parameters, modify the application behaviors, access and, potentially exploit, uncontrollable variables, and bypass input validation checkpoints and WAF rules.
  • OS Command Injection CAPEC-88 In this type of an attack, an adversary injects operating system commands into existing application functions. An application that uses untrusted input to build command strings is vulnerable. An adversary can leverage OS command injection in an application to elevate privileges, execute arbitrary commands and compromise the underlying operating system.

Vulnerable Configurations

  • cpe:2.3:a:shescape_project:shescape:0.1.0:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:0.1.0:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:0.2.0:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:0.2.0:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:0.2.1:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:0.2.1:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:0.3.0:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:0.3.0:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:0.3.1:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:0.3.1:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:0.4.0:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:0.4.0:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:0.4.1:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:0.4.1:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:1.0.0:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:1.0.0:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:1.1.0:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:1.1.0:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:1.1.1:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:1.1.1:*:*:*:*:node.js:*:*
  • cpe:2.3:a:shescape_project:shescape:1.1.2:*:*:*:*:node.js:*:*
    cpe:2.3:a:shescape_project:shescape:1.1.2:*:*:*:*:node.js:*:*
  • cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*
    cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*
  • cpe:2.3:o:opengroup:unix:-:*:*:*:*:*:*:*
    cpe:2.3:o:opengroup:unix:-:*:*:*:*:*:*:*

Protect Your Infrastructure against CVE-2021-21384: Combat Critical CVE Threats

Stay updated with real-time CVE vulnerabilities and take action to secure your systems. Enhance your cybersecurity posture with the latest threat intelligence and mitigation techniques. Develop the skills necessary to defend against CVEs and secure critical infrastructures. Join the top cybersecurity professionals safeguarding today's infrastructures.

Other 5 Recently Published CVEs Vulnerabilities

  • CVE-2025-31203 – An integer overflow was addressed with improved input validation. This issue is fixed in macOS Sequoia 15.4, tvOS 18.4, iPadOS 17.7.6, macOS Sonoma...
  • CVE-2025-31202 – A null pointer dereference was addressed with improved input validation. This issue is fixed in iOS 18.4 and iPadOS 18.4, macOS Sequoia 15.4, tvOS ...
  • CVE-2025-31197 – The issue was addressed with improved checks. This issue is fixed in macOS Sequoia 15.4, tvOS 18.4, macOS Ventura 13.7.5, iPadOS 17.7.6, macOS Sono...
  • CVE-2025-30445 – A type confusion issue was addressed with improved checks. This issue is fixed in macOS Sequoia 15.4, tvOS 18.4, macOS Ventura 13.7.5, iPadOS 17.7....
  • CVE-2025-24271 – An access issue was addressed with improved access restrictions. This issue is fixed in macOS Sequoia 15.4, tvOS 18.4, macOS Ventura 13.7.5, iPadOS...