CVE-2020-8127: Reveal.js Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-6vwx-mwp8-fh44
Share
CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2020-8127 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Reveal.js libraries in the npm ecosystem. The issue involves cross-site scripting in reveal.js. Remediation is available by upgrading affected packages to version 3.9.2.

CVE-2020-8127 at a Glance

CVE Identifier CVE-2020-8127
GHSA Identifier GHSA-6vwx-mwp8-fh44
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 Reveal.js
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-2020-8127

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

reveal.js fixed: 3.9.2 
npm install reveal.js@3.9.2
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 reveal.js

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-8127, inspect your project dependencies using npm:

npm ls reveal.js

Analyze the terminal output to locate any version of Reveal.js in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.9.2), your application is affected.

Note: The npm ls reveal.js 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 Reveal.js, 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

Insufficient validation in cross-origin communication (postMessage) in reveal.js version 3.9.1 and earlier allow attackers to perform cross-site scripting attacks.

CVE-2020-8127 Affected Reveal.js Versions

1 component(s)
Fixed Versions:
3.9.2
Product / Package Ecosystem Affected Versions Fixed Version
reveal.js
npm/reveal.js
npm
< 3.9.2
3.9.2

References

NVD — CVE-2020-8127 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-8127
hackerone.com/reports/691977 WEB
https://hackerone.com/reports/691977

Frequently Asked Questions

What is CVE-2020-8127?
CVE-2020-8127 is a security vulnerability in Reveal.js involving Cross-site Scripting in reveal.js under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Reveal.js versions are affected?
Affected versions include releases prior to 3.9.2 across affected packages: reveal.js.
What version fixes CVE-2020-8127?
Upgrading to 3.9.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is reveal.js affected?
Yes, reveal.js is affected in releases prior to 3.9.2. Upgrade your dependency to 3.9.2 or later.
What is the CVSS score of CVE-2020-8127?
CVE-2020-8127 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-2020-8127?
CVE-2020-8127 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-2020-8127?
Run the dependency tree command: 'npm ls reveal.js'. 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-6vwx-mwp8-fh44",
  "modified" : "2021-04-20T22:02:07Z",
  "published" : "2021-05-10T18:47:10Z",
  "aliases" : [ "CVE-2020-8127" ],
  "summary" : "Cross-site Scripting in reveal.js",
  "details" : "Insufficient validation in cross-origin communication (postMessage) in reveal.js version 3.9.1 and earlier allow attackers to perform cross-site scripting attacks.",
  "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" : "reveal.js"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.9.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.9.1"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-8127"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/691977"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-04-20T22:02:07Z",
    "nvd_published_at" : "2020-02-28T20:15:00Z"
  }
}