CVE-2020-27224: @theia/preview Cross-Site Scripting Vulnerability

CRITICAL
Advisory Identifier: GHSA-gcm9-cc3r-c6vj
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CVSS 9.6
CWE-79
Published
Advisory Summary

CVE-2020-27224 is a CRITICAL (CVSS 9.6) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting @theia/preview libraries in the npm ecosystem. The issue involves cross-site scripting (xss) in eclipse theia. Remediation is available by upgrading affected packages to version 1.3.0.

CVE-2020-27224 at a Glance

CVE Identifier CVE-2020-27224
GHSA Identifier GHSA-gcm9-cc3r-c6vj
Severity CRITICAL
CVSS v3.1 Base Score 9.6
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product @theia/preview
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 9.6

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:H/I:H/A:H).

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 High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2020-27224

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

@theia/preview fixed: 1.3.0 
npm install @theia/preview@1.3.0
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 @theia/preview

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-27224, inspect your project dependencies using npm:

npm ls @theia/preview

Analyze the terminal output to locate any version of @theia/preview in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.3.0), your application is affected.

Note: The npm ls @theia/preview 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 @theia/preview, 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

In Eclipse Theia versions up to and including 1.2.0, the Markdown Preview (@theia/preview), can be exploited to execute arbitrary code.

CVE-2020-27224 Affected @theia/preview Versions

1 component(s)
Fixed Versions:
1.3.0
Product / Package Ecosystem Affected Versions Fixed Version
@theia/preview
npm/@theia/preview
npm
< 1.3.0
1.3.0

References

NVD — CVE-2020-27224 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-27224
@theia/preview Source Repository REPOSITORY
https://github.com/eclipse-theia/theia/issues/7954
@theia/preview Source Repository REPOSITORY
https://github.com/eclipse-theia/theia/pull/7971
omespino.com/write-up-google-bug... WEB
https://omespino.com/write-up-google-bug-bounty-xss-to-cloud-shell-instance-takeover-rce-as-root-5000-usd

Frequently Asked Questions

What is CVE-2020-27224?
CVE-2020-27224 is a security vulnerability in @theia/preview involving Cross-site Scripting (XSS) in Eclipse Theia under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which @theia/preview versions are affected?
Affected versions include releases prior to 1.3.0 across affected packages: @theia/preview.
What version fixes CVE-2020-27224?
Upgrading to 1.3.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @theia/preview affected?
Yes, @theia/preview is affected in releases prior to 1.3.0. Upgrade your dependency to 1.3.0 or later.
What is the CVSS score of CVE-2020-27224?
CVE-2020-27224 has a CVSS v3.1 base score of 9.6 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2020-27224?
CVE-2020-27224 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-2020-27224?
Run the dependency tree command: 'npm ls @theia/preview'. 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-gcm9-cc3r-c6vj",
  "modified" : "2021-03-29T22:10:04Z",
  "published" : "2021-04-13T15:18:09Z",
  "aliases" : [ "CVE-2020-27224" ],
  "summary" : "Cross-site Scripting (XSS) in Eclipse Theia",
  "details" : "In Eclipse Theia versions up to and including 1.2.0, the Markdown Preview (@theia/preview), can be exploited to execute arbitrary code.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@theia/preview"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.3.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "< 1.2.0"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-27224"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/eclipse-theia/theia/issues/7954"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/eclipse-theia/theia/pull/7971"
  }, {
    "type" : "WEB",
    "url" : "https://omespino.com/write-up-google-bug-bounty-xss-to-cloud-shell-instance-takeover-rce-as-root-5000-usd"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-03-29T22:10:04Z",
    "nvd_published_at" : "2021-02-24T17:15:00Z"
  }
}