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Improper Restriction of XML External Entity Reference (XXE) in Nokogiri on JRuby

High severity GitHub Reviewed Published Sep 27, 2021 in sparklemotion/nokogiri • Updated May 4, 2023

Package

bundler nokogiri (RubyGems)

Affected versions

<= 1.12.4

Patched versions

1.12.5

Description

Severity

The Nokogiri maintainers have evaluated this as High Severity 7.5 (CVSS3.0) for JRuby users. (This security advisory does not apply to CRuby users.)

Impact

In Nokogiri v1.12.4 and earlier, on JRuby only, the SAX parser resolves external entities by default.

Users of Nokogiri on JRuby who parse untrusted documents using any of these classes are affected:

  • Nokogiri::XML::SAX::Parser
  • Nokogiri::HTML4::SAX::Parser or its alias Nokogiri::HTML::SAX::Parser
  • Nokogiri::XML::SAX::PushParser
  • Nokogiri::HTML4::SAX::PushParser or its alias Nokogiri::HTML::SAX::PushParser

Mitigation

JRuby users should upgrade to Nokogiri v1.12.5 or later. There are no workarounds available for v1.12.4 or earlier.

CRuby users are not affected.

References

@flavorjones flavorjones published to sparklemotion/nokogiri Sep 27, 2021
Reviewed Sep 27, 2021
Published to the GitHub Advisory Database Sep 27, 2021
Published by the National Vulnerability Database Sep 27, 2021
Last updated May 4, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS score

0.136%
(50th percentile)

Weaknesses

CVE ID

CVE-2021-41098

GHSA ID

GHSA-2rr5-8q37-2w7h

Source code

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