CVE-2019-25103 in simple-markdown
Summary
by MITRE • 02/12/2023
A vulnerability has been found in simple-markdown 0.5.1 and classified as problematic. Affected by this vulnerability is an unknown functionality of the file simple-markdown.js. The manipulation leads to inefficient regular expression complexity. The attack can be launched remotely. Upgrading to version 0.5.2 is able to address this issue. The name of the patch is 89797fef9abb4cab2fb76a335968266a92588816. It is recommended to upgrade the affected component. The associated identifier of this vulnerability is VDB-220639.
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Analysis
by VulDB Data Team • 03/10/2023
The vulnerability identified as CVE-2019-25103 represents a critical security flaw in the simple-markdown JavaScript library version 0.5.1, specifically targeting the regular expression implementation within the simple-markdown.js file. This issue manifests as inefficient regular expression complexity that can be exploited through remote attack vectors, making it particularly dangerous for web applications that rely on markdown parsing functionality. The vulnerability stems from the library's handling of regular expressions during markdown parsing operations, where poorly constructed patterns can lead to exponential time complexity during processing.
The technical flaw in this vulnerability aligns with CWE-1321, which specifically addresses inefficient regular expression complexity that can lead to denial of service conditions. When malicious input is processed through the vulnerable markdown parser, the regular expressions employed in the simple-markdown.js file can experience catastrophic backtracking, causing the parsing engine to consume excessive computational resources. This behavior creates a potential denial of service scenario where an attacker can craft specific markdown input that will cause the application to hang or become unresponsive for extended periods.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged in remote exploitation scenarios where attackers can systematically consume server resources through carefully crafted markdown content. Applications that process user-generated markdown content, such as content management systems, wikis, and collaborative platforms, become particularly vulnerable to this attack vector. The remote nature of the exploit means that attackers can target these applications from external networks without requiring local access or authentication, making the vulnerability particularly attractive for automated attack campaigns.
Security practitioners should consider this vulnerability in the context of the MITRE ATT&CK framework, specifically under the technique T1499.3 for Network Denial of Service, as the vulnerability enables attackers to consume system resources through malformed input processing. The recommended mitigation strategy involves upgrading to version 0.5.2 of the simple-markdown library, which incorporates the patch identified by the commit hash 89797fef9abb4cab2fb76a335968266a92588816. This upgrade addresses the underlying regular expression complexity issues by implementing more efficient pattern matching algorithms and preventing the catastrophic backtracking scenarios that enabled the vulnerability. Organizations should prioritize this patch deployment across all systems utilizing the affected library, particularly those processing untrusted markdown input from users or external sources.