CVE-2022-37620 in html-minifier
Summary
by MITRE • 10/31/2022
A Regular Expression Denial of Service (ReDoS) flaw was found in kangax html-minifier 4.0.0 via the candidate variable in htmlminifier.js.
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Analysis
by VulDB Data Team • 11/04/2024
The vulnerability identified as CVE-2022-37620 represents a critical Regular Expression Denial of Service flaw within the kangax html-minifier version 4.0.0. This issue specifically manifests through the candidate variable within the htmlminifier.js file, creating a significant security risk for applications that rely on this popular HTML minification library. The flaw enables attackers to craft malicious input that can cause the regular expression engine to consume excessive computational resources, leading to system performance degradation or complete service unavailability. The vulnerability impacts any system or application that utilizes this version of html-minifier for processing HTML content, making it particularly concerning given the library's widespread adoption in web development workflows.
The technical implementation of this vulnerability stems from the improper handling of regular expressions within the html-minifier library's candidate variable processing logic. When malicious input is passed through the minification process, the regular expression patterns become susceptible to catastrophic backtracking scenarios where the regex engine must explore an exponential number of possible matching paths. This behavior is characteristic of ReDoS vulnerabilities and directly maps to CWE-1321, which specifically addresses Regular Expression Denial of Service vulnerabilities. The flaw occurs because the library fails to properly validate or sanitize input before processing it through vulnerable regular expression patterns, allowing attackers to exploit the backtracking behavior by crafting input strings that trigger worst-case performance scenarios in the regex engine.
The operational impact of CVE-2022-37620 extends beyond simple performance degradation to potentially enable complete system compromise through denial of service attacks. Attackers can leverage this vulnerability to consume excessive CPU cycles and memory resources on systems processing HTML content through the affected library, potentially causing application crashes, service interruptions, or resource exhaustion that affects system availability. This vulnerability particularly impacts web applications, content management systems, and any platform that processes user-generated HTML content through html-minifier. The attack vector is straightforward - an attacker simply needs to provide maliciously crafted input that triggers the vulnerable regular expression patterns, making it a low-effort but high-impact security risk that can be exploited across various deployment environments.
Mitigation strategies for CVE-2022-37620 should prioritize immediate version updates to the html-minifier library, specifically upgrading to versions that contain patches addressing the identified ReDoS vulnerability. Organizations should implement input validation and sanitization measures at application boundaries to prevent malicious input from reaching the vulnerable code paths, although this approach provides only partial protection. The remediation process should include comprehensive testing to ensure that updated versions maintain application functionality while eliminating the vulnerability. Security teams should also consider implementing rate limiting and resource monitoring to detect and prevent exploitation attempts, aligning with ATT&CK technique T1499.004 for network denial of service. Additionally, organizations should conduct thorough vulnerability assessments of their entire software supply chain to identify other potential ReDoS vulnerabilities in similar libraries and dependencies that may pose similar risks to their operational security posture.