Vulnerabilities in pkg:npm/phoenix_html

PACKAGE
Advisory Identifier: GHSA-5g2h-9x5v-5h3x
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Advisory Summary

CVE-2021-46871 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Phoenix html libraries in the npm ecosystem. The issue involves phoenix_html allows cross-site scripting in heex class attributes. Remediation is available by upgrading affected packages to version 3.0.4.

1 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/phoenix_html

1 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/phoenix_html. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-5g2h-9x5v-5h3x CVE-2021-46871 MODERATE phoenix_html allows Cross-site Scripting in HEEx class attributes

CVE-2021-46871 at a Glance

CVE Identifier CVE-2021-46871
GHSA Identifier GHSA-5g2h-9x5v-5h3x
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Phoenix html
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 6.1

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

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
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-2021-46871

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

phoenix_html fixed: 3.0.4 
npm install phoenix_html@3.0.4
phoenix_html fixed: 3.0.4 
Upgrade phoenix_html to 3.0.4
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 phoenix_html

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-46871, inspect your project dependencies using npm:

npm ls phoenix_html

Analyze the terminal output to locate any version of Phoenix html in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.0.4), your application is affected.

Note: The npm ls phoenix_html 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 Phoenix html, 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

tag.ex in Phoenix Phoenix.HTML (aka phoenix_html) before 3.0.4 allows XSS in HEEx class attributes

CVE-2021-46871 Affected Phoenix html Versions

2 component(s)
Fixed Versions:
3.0.4
Product / Package Ecosystem Affected Versions Fixed Version
phoenix_html
npm/phoenix_html
npm
< 3.0.4
3.0.4
phoenix_html
 Hex
< 3.0.4
3.0.4

References

NVD — CVE-2021-46871 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-46871
Security Fix Commit FIX COMMIT
https://github.com/phoenixframework/phoenix_html/commit/62a0139fb716bcdce697f6221244bd81d321d620
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-j3gg-r6gp-95q2
Phoenix html Source Repository REPOSITORY
https://github.com/phoenixframework/phoenix_html

Frequently Asked Questions

What is CVE-2021-46871?
CVE-2021-46871 is a security vulnerability in Phoenix html involving phoenix_html allows Cross-site Scripting in HEEx class attributes under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Phoenix html versions are affected?
Affected versions include releases prior to 3.0.4 across affected packages: phoenix_html.
What version fixes CVE-2021-46871?
Upgrading to 3.0.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is phoenix_html affected?
Yes, phoenix_html is affected in releases prior to 3.0.4. Upgrade your dependency to 3.0.4 or later.
What is the CVSS score of CVE-2021-46871?
CVE-2021-46871 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-46871?
CVE-2021-46871 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-2021-46871?
Run the dependency tree command: 'npm ls phoenix_html'. 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-5g2h-9x5v-5h3x",
  "modified" : "2025-04-09T19:57:45Z",
  "published" : "2023-01-10T06:30:25Z",
  "aliases" : [ "CVE-2021-46871" ],
  "summary" : "phoenix_html allows Cross-site Scripting in HEEx class attributes",
  "details" : "tag.ex in Phoenix Phoenix.HTML (aka phoenix_html) before 3.0.4 allows XSS in HEEx class attributes",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "phoenix_html"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.0.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "phoenix_html"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.0.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-46871"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/phoenixframework/phoenix_html/commit/62a0139fb716bcdce697f6221244bd81d321d620"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-j3gg-r6gp-95q2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/phoenixframework/phoenix_html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-01-10T22:16:31Z",
    "nvd_published_at" : "2023-01-10T06:15:00Z"
  }
}