CVE-2021-4231: @angular/core Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-c75v-2vq8-878f
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CVSS 5.4
CWE-79
Published
Advisory Summary

CVE-2021-4231 is a MODERATE (CVSS 5.4) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting @angular/core libraries in the npm ecosystem. The issue involves angular vulnerable to cross-site scripting. Remediation is available by upgrading affected packages to version 11.0.5, 11.1.0-next.3, 10.2.5.

CVE-2021-4231 at a Glance

CVE Identifier CVE-2021-4231
GHSA Identifier GHSA-c75v-2vq8-878f
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product @angular/core
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2021-4231

To remediate this vulnerability, upgrade all affected @angular/core dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

@angular/core fixed: 11.0.5 
npm install @angular/core@11.0.5
@angular/core fixed: 11.1.0-next.3 
npm install @angular/core@11.1.0-next.3
@angular/core fixed: 10.2.5 
npm install @angular/core@10.2.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @angular/core

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-4231, inspect your project dependencies using npm:

npm ls @angular/core

Analyze the terminal output to locate any version of @angular/core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 11.0.5), your application is affected.

Note: The npm ls @angular/core command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In @angular/core, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

A vulnerability was found in Angular up to 11.0.4/11.1.0-next.2. It has been classified as problematic. Affected is the handling of comments. The manipulation leads to cross site scripting. It is possible to launch the attack remotely but it might require an authentication first. Upgrading to version 10.2.5, 11.0.5 or 11.1.0-next.3 is advised to to address this issue.

CVE-2021-4231 Affected @angular/core Versions

3 component(s)
Fixed Versions:
11.0.511.1.0-next.310.2.5
Product / Package Ecosystem Affected Versions Fixed Version
@angular/core
npm/@angular/core
npm
≥ 11.0.0
< 11.0.5
11.0.5
@angular/core
npm/@angular/core
npm
≥ 11.1.0-next.0
< 11.1.0-next.3
11.1.0-next.3
@angular/core
npm/@angular/core
npm
< 10.2.5
10.2.5

References

NVD — CVE-2021-4231 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-4231
@angular/core Source Repository REPOSITORY
https://github.com/angular/angular/issues/40136
Security Fix Commit FIX COMMIT
https://github.com/angular/angular/commit/0aa220bc0000fc4d1651ec388975bbf5baa1da36
Security Fix Commit FIX COMMIT
https://github.com/angular/angular/commit/47d9b6d72dab9d60c96bc1c3604219f6385649ea
Security Fix Commit FIX COMMIT
https://github.com/angular/angular/commit/ba8da742e3b243e8f43d4c63aa842b44e14f2b09
@angular/core Source Repository REPOSITORY
https://github.com/angular/angular
@angular/core Security Information SECURITY
https://security.snyk.io/vuln/SNYK-JS-ANGULARCORE-1070902
vuldb.com/ WEB
https://vuldb.com/?id.181356

Frequently Asked Questions

What is CVE-2021-4231?
CVE-2021-4231 is a security vulnerability in @angular/core involving Angular vulnerable to Cross-site Scripting under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which @angular/core versions are affected?
Affected versions include releases prior to 11.0.5, 11.1.0-next.3, 10.2.5 across affected packages: @angular/core.
What version fixes CVE-2021-4231?
Upgrading to 11.0.5, 11.1.0-next.3, 10.2.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @angular/core affected?
Yes, @angular/core is affected in releases prior to 11.0.5, 11.1.0-next.3, 10.2.5. Upgrade your dependency to 11.0.5, 11.1.0-next.3, 10.2.5 or later.
What is the CVSS score of CVE-2021-4231?
CVE-2021-4231 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-4231?
CVE-2021-4231 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2021-4231?
Run the dependency tree command: 'npm ls @angular/core'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-c75v-2vq8-878f",
  "modified" : "2025-11-20T21:47:22Z",
  "published" : "2022-05-27T00:01:08Z",
  "aliases" : [ "CVE-2021-4231" ],
  "summary" : "Angular vulnerable to Cross-site Scripting",
  "details" : "A vulnerability was found in Angular up to 11.0.4/11.1.0-next.2. It has been classified as problematic. Affected is the handling of comments. The manipulation leads to cross site scripting. It is possible to launch the attack remotely but it might require an authentication first. Upgrading to version 10.2.5, 11.0.5 or 11.1.0-next.3 is advised to to address this issue.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
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    },
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      "events" : [ {
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    } ],
    "database_specific" : {
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  }, {
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    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-4231"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/issues/40136"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/commit/0aa220bc0000fc4d1651ec388975bbf5baa1da36"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/commit/47d9b6d72dab9d60c96bc1c3604219f6385649ea"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/commit/ba8da742e3b243e8f43d4c63aa842b44e14f2b09"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/angular/angular"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-JS-ANGULARCORE-1070902"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/?id.181356"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-06-02T18:58:52Z",
    "nvd_published_at" : "2022-05-26T14:15:00Z"
  }
}