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GHSA-crjr-9rc5-ghw8 CVE-2022-24836

Nokogiri Inefficient Regular Expression Complexity

High RubyGems
Severity
7.5 / 10
High · CVSS 3.1
Exploit chance (EPSS)
3.52%
Chance of exploitation in the next 30 days. Higher than 89.22% of scored vulnerabilities.
Known exploited
No
Not in CISA's catalog
Weakness
CWE-1333 Inefficient Regular Expression Complexity
CWE-400 Uncontrolled Resource Consumption
Fix
1.13.4
Upgrade nokogiri to this version or later

Description

Summary

Nokogiri < v1.13.4 contains an inefficient regular expression that is susceptible to excessive backtracking when attempting to detect encoding in HTML documents.

Mitigation

Upgrade to Nokogiri >= 1.13.4.

Severity

The Nokogiri maintainers have evaluated this as High Severity 7.5 (CVSS3.1).

References

CWE-1333 Inefficient Regular Expression Complexity

Credit

This vulnerability was reported by HackerOne user ooooooo_q (ななおく).

Affected versions

RubyGems

PackageVulnerableFixed in
nokogiri
< 1.13.4
1.13.4

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

nokogiri RubyGems → 1.13.4

bundler
bundle update nokogiri # Gemfile: gem "nokogiri", ">= 1.13.4"

Severity breakdown

CVSS 3.1 7.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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

Weakness

CWE-1333: Inefficient Regular Expression Complexity

The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.

How to prevent it
  • Architecture and Design: Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
  • System Configuration: Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
  • Implementation: Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
  • Implementation: Limit the length of the input that the regular expression will process.

CWE-400: Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource.

How to prevent it
  • Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
  • Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
  • Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
  • Implementation: Ensure that all failures in resource allocation place the system into a safe posture.

References

Advisories

Packages

Other links

Timeline

  1. Published
  2. Last updated by the source
  3. Latest EPSS score
AdvisorySeverityWhy it's related
GHSA-phwj-rprq-35pp
Nokogiri: Possible Use-After-Free when setting an attribute value via `Nokogiri::XML::Attr#value=` or `#content=`
High Also affects nokogiri
GHSA-wfpw-mmfh-qq69
Nokogiri: Possible Use-After-Free in XInclude Processing
Low Also affects nokogiri
GHSA-p67v-3w7g-wjg7
Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime
Medium Also affects nokogiri
GHSA-wjv4-x9w8-wm3h
Nokogiri: Possible Use-After-Free when setting `Document#root=` to an invalid node type
Medium Also affects nokogiri
GHSA-5prr-v3j2-97mh
Nokogiri: Possible Out-of-Bounds Read in `Nokogiri::XML::NodeSet#[]`
High Also affects nokogiri
GHSA-9cv2-cfxc-v4v2
Nokogiri: Null Pointer Dereference calling methods on uninitialized wrapper classes
High Also affects nokogiri
GHSA-8678-w3jw-xfc2
Nokogiri: XML::Schema on JRuby allows network requests when NONET is set, bypassing CVE-2020-26247
Low Also affects nokogiri
GHSA-5v8h-3h3q-446p
Nokogiri: Possible Use-After-Free when `Nokogiri::XML::Document#encoding=` raises an exception
High Also affects nokogiri
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