CyberSecBulletin
CVE-2022-24836NVD status: Modified

nokogiri: Inefficient Regular Expression Complexity

Published Updated By the CyberSecBulletin desk

CVE-2022-24836 is a high-severity inefficient regular expression complexity vulnerability in nokogiri from Sparklemotion, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected nokogiri versions: < 1.13.4. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 3.52% chance of exploitation within 30 days, higher than 89% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update macOS to 13.1 or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Sparklemotionnokogiri< 1.13.4Not stated
Fedora ProjectFedora34; 35; 36Not stated
DebianDebian Linux9.0; 10.0Not stated
ApplemacOS13.0 up to, but not including, 13.113.1

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighCNA (github.com)
CVSS 3.17.5HighNVD
CVSS 2.05.0MediumNVD

Official description

Nokogiri is an open source XML and HTML library for Ruby. Nokogiri `< v1.13.4` contains an inefficient regular expression that is susceptible to excessive backtracking when attempting to detect encoding in HTML documents. Users are advised to upgrade to Nokogiri `>= 1.13.4`. There are no known workarounds for this issue.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Inefficient Regular Expression Complexity

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

How developers prevent this class of flaw

  • Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
  • 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.
  • Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.

More Inefficient Regular Expression Complexity vulnerabilities (CWE-1333)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in nokogiri

All nokogiri vulnerabilities

Recent Inefficient Regular Expression Complexity vulnerabilities

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