CVE-2021-21366 Vulnerability Analysis & Exploit Details

CVE-2021-21366
Vulnerability Scoring

4.3
/10
Medium Risk

The vulnerability CVE-2021-21366 could compromise system integrity but typically requires user interaction to be exploited.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Unchanged
    Exploit remains within the originally vulnerable component.
  • User Interaction: Required
    User interaction is necessary for successful exploitation.

CVE-2021-21366 Details

Status: Modified

Last updated: 🕠 21 Nov 2024, 05:48 UTC
Originally published on: 🕔 12 Mar 2021, 17:15 UTC

Time between publication and last update: 1349 days

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2021-21366 Vulnerability Summary

CVE-2021-21366: xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. xmldom versions 0.4.0 and older do not correctly preserve system identifiers, FPIs or namespaces when repeatedly parsing and serializing maliciously crafted documents. This may lead to unexpected syntactic changes during XML processing in some downstream applications. This is fixed in version 0.5.0. As a workaround downstream applications can validate the input and reject the maliciously crafted documents.

Assessing the Risk of CVE-2021-21366

Access Complexity Graph

The exploitability of CVE-2021-21366 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-2021-21366

With low attack complexity and no required privileges, CVE-2021-21366 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.

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-2021-21366, 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-2021-21366, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2021-21366 has no significant impact on data confidentiality.
  • Integrity: Low
    Exploiting CVE-2021-21366 may cause minor changes to data without severely impacting its accuracy.
  • Availability: None
    CVE-2021-21366 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: 0.15% (probability of exploit)

EPSS Percentile: 52.45% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 47.55% of others.

CVE-2021-21366 References

External References

CWE Common Weakness Enumeration

CWE-436

CAPEC Common Attack Pattern Enumeration and Classification

  • HTTP Request Splitting CAPEC-105 An adversary abuses the flexibility and discrepancies in the parsing and interpretation of HTTP Request messages by different intermediary HTTP agents (e.g., load balancer, reverse proxy, web caching proxies, application firewalls, etc.) to split a single HTTP request into multiple unauthorized and malicious HTTP requests to a back-end HTTP agent (e.g., web server). See CanPrecede relationships for possible consequences.
  • HTTP Response Smuggling CAPEC-273 An adversary manipulates and injects malicious content in the form of secret unauthorized HTTP responses, into a single HTTP response from a vulnerable or compromised back-end HTTP agent (e.g., server). See CanPrecede relationships for possible consequences. Modification/manipulation of HTTP message headers, request-line and body parameters to disrupt and interfere in the interpretation and parsing of HTTP message lengths/boundaries for consecutive HTTP messages by HTTP agents in a HTTP chain or network path.
  • HTTP Response Splitting CAPEC-34 An adversary manipulates and injects malicious content, in the form of secret unauthorized HTTP responses, into a single HTTP response from a vulnerable or compromised back-end HTTP agent (e.g., web server) or into an already spoofed HTTP response from an adversary controlled domain/site. See CanPrecede relationships for possible consequences.

Vulnerable Configurations

  • cpe:2.3:a:xmldom_project:xmldom:-:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:-:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.0:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.0:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.1:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.1:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.2:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.2:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.3:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.3:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.4:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.4:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.5:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.5:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.6:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.6:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.7:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.7:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.8:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.8:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.9:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.9:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.10:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.10:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.11:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.11:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.12:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.12:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.13:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.13:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.14:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.14:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.15:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.15:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.16:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.16:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.17:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.17:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.18:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.18:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.19:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.19:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.20:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.20:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.21:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.21:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.22:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.22:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.24:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.24:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.25:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.25:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.26:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.26:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.27:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.27:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.29:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.29:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.30:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.30:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.1.31:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.1.31:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.2.0:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.2.0:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.2.1:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.2.1:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.3.0:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.3.0:-:*:*:*:node.js:*:*
  • cpe:2.3:a:xmldom_project:xmldom:0.4.0:-:*:*:*:node.js:*:*
    cpe:2.3:a:xmldom_project:xmldom:0.4.0:-:*:*:*:node.js:*:*
  • cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
    cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

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