CVE-2022-23516: Uncontrolled Recursion in Loofah

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-12-14 · updated 2026-06-17
Weakness: CWE-674

Description

Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. Loofah >= 2.2.0, < 2.19.1 uses recursion for sanitizing CDATA sections, making it susceptible to stack exhaustion and raising a SystemStackError exception. This may lead to a denial of service through CPU resource consumption. This issue is patched in version 2.19.1. Users who are unable to upgrade may be able to mitigate this vulnerability by limiting the length of the strings that are sanitized.

Affected products

flavorjones loofah: from 2.2.0 before 2.19.1 — fixed in 2.19.1
Rubygems Loofah: from 2.2.0 before 2.19.1; 2.10.0, 2.11.0, 2.12.0, 2.13.0, 2.14.0, 2.15.0 (+17) — fixed in 2.19.1

How to fix

Upgrade to a fixed version: flavorjones loofah 2.19.1; Rubygems Loofah 2.19.1. Check the vendor advisory for mitigations.

References

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