CVE-2019-5477: Nokogiri Nokogiri Command Injection Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-cr5j-953j-xw5p
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CVSS 9.8
CWE-78
Published
Advisory Summary

CVE-2019-5477 is a CRITICAL (CVSS 9.8) nokogiri command injection vulnerability vulnerability (CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')) affecting Nokogiri libraries in the RubyGems ecosystem. The issue involves nokogiri command injection vulnerability. Remediation is available by upgrading affected packages to version 1.10.4, 1.0.7.

CVE-2019-5477 at a Glance

CVE Identifier CVE-2019-5477
GHSA Identifier GHSA-cr5j-953j-xw5p
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Affected Product Nokogiri
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 9.8

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:N/S:U/C:H/I:H/A:H).

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

How to Fix CVE-2019-5477

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

nokogiri fixed: 1.10.4 
Upgrade nokogiri to 1.10.4
rexical fixed: 1.0.7 
Upgrade rexical to 1.0.7
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 nokogiri

How to Check if You Are Affected

To determine whether your application is affected by CVE-2019-5477, inspect your project dependencies for Nokogiri:

inspect dependencies for nokogiri

Analyze the terminal output to locate any version of Nokogiri in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.10.4), 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-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'), where the product constructs all or part of an os command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended os command when it is sent to a downstream component. In Nokogiri, 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 command injection vulnerability in Nokogiri v1.10.3 and earlier allows commands to be executed in a subprocess via Ruby's `Kernel.open` method. Processes are vulnerable only if the undocumented method `Nokogiri::CSS::Tokenizer#load_file` is being called with unsafe user input as the filename. This vulnerability appears in code generated by the Rexical gem versions v1.0.6 and earlier. Rexical is used by Nokogiri to generate lexical scanner code for parsing CSS queries. The underlying vulnerability was addressed in Rexical v1.0.7 and Nokogiri upgraded to this version of Rexical in Nokogiri v1.10.4.

CVE-2019-5477 Affected Nokogiri Versions

2 component(s)
Fixed Versions:
1.10.41.0.7
Product / Package Ecosystem Affected Versions Fixed Version
nokogiri
gem/nokogiri
RubyGems
< 1.10.4
1.10.4
rexical
gem/rexical
RubyGems
< 1.0.7
1.0.7

References

NVD — CVE-2019-5477 NVD
https://nvd.nist.gov/vuln/detail/CVE-2019-5477
Nokogiri Source Repository REPOSITORY
https://github.com/sparklemotion/nokogiri/issues/1915
Security Fix Commit FIX COMMIT
https://github.com/sparklemotion/nokogiri/commit/5d30128343573a9428c86efc758ba2c66e9f12dc
Security Fix Commit FIX COMMIT
https://github.com/tenderlove/rexical/commit/a652474dbc66be350055db3e8f9b3a7b3fd75926
hackerone.com/reports/650835 WEB
https://hackerone.com/reports/650835
Nokogiri Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/nokogiri/CVE-2019-5477.yml
Nokogiri Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rexical/CVE-2019-5477.yml
Nokogiri Source Repository REPOSITORY
https://github.com/sparklemotion/nokogiri
Nokogiri Source Repository REPOSITORY
https://github.com/tenderlove/rexical/blob/master/CHANGELOG.rdoc
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2019/09/msg00027.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2022/10/msg00018.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2022/10/msg00019.html
Nokogiri Security Information SECURITY
https://security.gentoo.org/glsa/202006-05
usn.ubuntu.com/4175-1 WEB
https://usn.ubuntu.com/4175-1

Frequently Asked Questions

What is CVE-2019-5477?
CVE-2019-5477 is a security vulnerability in Nokogiri involving Nokogiri Command Injection Vulnerability under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection').
Which Nokogiri versions are affected?
Affected versions include releases prior to 1.10.4, 1.0.7 across affected packages: nokogiri, rexical.
What version fixes CVE-2019-5477?
Upgrading to 1.10.4, 1.0.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is nokogiri affected?
Yes, nokogiri is affected in releases prior to 1.10.4. Upgrade your dependency to 1.10.4 or later.
Is rexical affected?
Yes, rexical is affected in releases prior to 1.0.7. Upgrade your dependency to 1.0.7 or later.
What is the CVSS score of CVE-2019-5477?
CVE-2019-5477 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2019-5477?
CVE-2019-5477 is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') (The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.).
How can I check RubyGems dependencies for CVE-2019-5477?
Run the dependency tree command: 'inspect dependencies for nokogiri'. 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-cr5j-953j-xw5p",
  "modified" : "2023-08-28T14:05:24Z",
  "published" : "2019-08-19T19:27:23Z",
  "aliases" : [ "CVE-2019-5477" ],
  "summary" : "Nokogiri Command Injection Vulnerability",
  "details" : "A command injection vulnerability in Nokogiri v1.10.3 and earlier allows commands to be executed in a subprocess via Ruby's `Kernel.open` method. Processes are vulnerable only if the undocumented method `Nokogiri::CSS::Tokenizer#load_file` is being called with unsafe user input as the filename. This vulnerability appears in code generated by the Rexical gem versions v1.0.6 and earlier. Rexical is used by Nokogiri to generate lexical scanner code for parsing CSS queries. The underlying vulnerability was addressed in Rexical v1.0.7 and Nokogiri upgraded to this version of Rexical in Nokogiri v1.10.4.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "nokogiri"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.10.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "rexical"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.0.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2019-5477"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sparklemotion/nokogiri/issues/1915"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sparklemotion/nokogiri/commit/5d30128343573a9428c86efc758ba2c66e9f12dc"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/tenderlove/rexical/commit/a652474dbc66be350055db3e8f9b3a7b3fd75926"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/650835"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/nokogiri/CVE-2019-5477.yml"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rexical/CVE-2019-5477.yml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/sparklemotion/nokogiri"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/tenderlove/rexical/blob/master/CHANGELOG.rdoc"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2019/09/msg00027.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2022/10/msg00018.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2022/10/msg00019.html"
  }, {
    "type" : "WEB",
    "url" : "https://security.gentoo.org/glsa/202006-05"
  }, {
    "type" : "WEB",
    "url" : "https://usn.ubuntu.com/4175-1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2019-08-19T19:26:57Z",
    "nvd_published_at" : "2019-08-16T16:15:00Z"
  }
}