CVE-2020-26298: Redcarpet Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-q3wr-qw3g-3p4h
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CVSS 6.8
CWE-79 CWE-74
Published
Advisory Summary

CVE-2020-26298 is a MODERATE (CVSS 6.8) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Redcarpet libraries in the RubyGems ecosystem. The issue involves injection/xss in redcarpet. Remediation is available by upgrading affected packages to version 3.5.1.

CVE-2020-26298 at a Glance

CVE Identifier CVE-2020-26298
GHSA Identifier GHSA-q3wr-qw3g-3p4h
Severity MODERATE
CVSS v3.1 Base Score 6.8
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Redcarpet
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 6.8

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:N/I:H/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 None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2020-26298

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

redcarpet fixed: 3.5.1 
Upgrade redcarpet to 3.5.1
Verify Direct and Transitive Dependencies

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

inspect dependencies for redcarpet

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-26298, inspect your project dependencies for Redcarpet:

inspect dependencies for redcarpet

Analyze the terminal output to locate any version of Redcarpet in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.5.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

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 Redcarpet, 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

Redcarpet is a Ruby library for Markdown processing. In Redcarpet before version 3.5.1, there is an injection vulnerability which can enable a cross-site scripting attack. In affected versions no HTML escaping was being performed when processing quotes. This applies even when the `:escape_html` option was being used. This is fixed in version 3.5.1 by the referenced commit.

CVE-2020-26298 Affected Redcarpet Versions

1 component(s)
Fixed Versions:
3.5.1
Product / Package Ecosystem Affected Versions Fixed Version
redcarpet
gem/redcarpet
RubyGems
< 3.5.1
3.5.1

References

NVD — CVE-2020-26298 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-26298
Security Fix Commit FIX COMMIT
https://github.com/vmg/redcarpet/commit/a699c82292b17c8e6a62e1914d5eccc252272793
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-q3wr-qw3g-3p4h
Redcarpet Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/redcarpet/CVE-2020-26298.yml
Redcarpet Source Repository REPOSITORY
https://github.com/vmg/redcarpet
Redcarpet Source Repository REPOSITORY
https://github.com/vmg/redcarpet/blob/master/CHANGELOG.md#version-351-security
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2021/01/msg00014.html
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BFMYDIONVWATY7EB6EARDVXT47AYCRNM
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FNO4ZZUPGAEUXKQL4G2HRIH7CUZKPCT6
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PXNNWHHAPREDM3XJDACYRTK7DBMUONBI
rubygems.org/gems/redcarpet WEB
https://rubygems.org/gems/redcarpet
Redcarpet Security Information SECURITY
https://www.debian.org/security/2021/dsa-4831

Frequently Asked Questions

What is CVE-2020-26298?
CVE-2020-26298 is a security vulnerability in Redcarpet involving Injection/XSS in Redcarpet under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Redcarpet versions are affected?
Affected versions include releases prior to 3.5.1 across affected packages: redcarpet.
What version fixes CVE-2020-26298?
Upgrading to 3.5.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is redcarpet affected?
Yes, redcarpet is affected in releases prior to 3.5.1. Upgrade your dependency to 3.5.1 or later.
What is the CVSS score of CVE-2020-26298?
CVE-2020-26298 has a CVSS v3.1 base score of 6.8 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:N.
What CWE is associated with CVE-2020-26298?
CVE-2020-26298 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 RubyGems dependencies for CVE-2020-26298?
Run the dependency tree command: 'inspect dependencies for redcarpet'. 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-q3wr-qw3g-3p4h",
  "modified" : "2022-10-07T20:41:40Z",
  "published" : "2021-01-11T19:06:10Z",
  "aliases" : [ "CVE-2020-26298" ],
  "summary" : "Injection/XSS in Redcarpet",
  "details" : "Redcarpet is a Ruby library for Markdown processing. In Redcarpet before version 3.5.1, there is an injection vulnerability which can enable a cross-site scripting attack. In affected versions no HTML escaping was being performed when processing quotes. This applies even when the `:escape_html` option was being used.  This is fixed in version 3.5.1 by the referenced commit.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "redcarpet"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.5.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-26298"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vmg/redcarpet/commit/a699c82292b17c8e6a62e1914d5eccc252272793"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-q3wr-qw3g-3p4h"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/redcarpet/CVE-2020-26298.yml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/vmg/redcarpet"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vmg/redcarpet/blob/master/CHANGELOG.md#version-351-security"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2021/01/msg00014.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BFMYDIONVWATY7EB6EARDVXT47AYCRNM"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FNO4ZZUPGAEUXKQL4G2HRIH7CUZKPCT6"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PXNNWHHAPREDM3XJDACYRTK7DBMUONBI"
  }, {
    "type" : "WEB",
    "url" : "https://rubygems.org/gems/redcarpet"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2021/dsa-4831"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-74", "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-01-11T19:05:42Z",
    "nvd_published_at" : "2021-01-11T19:15:00Z"
  }
}