CVE-2026-30235 in openproject
Summary
by MITRE • 03/11/2026
OpenProject is an open-source, web-based project management software. Prior to 17.2.0, this vulnerability occurs due to improper validation of OpenProject’s Markdown rendering, specifically in the hyperlink handling. This allows an attacker to inject malicious hyperlink payloads that perform DOM clobbering. DOM clobbering can crash or blank the entire page by overwriting native DOM functions with HTML elements, causing critical JavaScript calls to throw runtime errors during application initialization and halt further execution. This vulnerability is fixed in 17.2.0.
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Analysis
by VulDB Data Team • 03/14/2026
The vulnerability identified as CVE-2026-30235 affects OpenProject versions prior to 17.2.0 and represents a critical security flaw in the application's Markdown rendering engine. This issue stems from inadequate input validation mechanisms within the hyperlink processing functionality, creating a pathway for malicious actors to manipulate the application's behavior through carefully crafted hyperlink payloads. The vulnerability specifically targets the DOM clobbering attack vector, where attacker-controlled content can overwrite native JavaScript DOM functions with HTML elements, fundamentally disrupting the application's runtime environment. This flaw exists within the core rendering pipeline of OpenProject's web interface, making it particularly dangerous as it can affect all users interacting with Markdown content, including project descriptions, issue reports, and collaborative documentation features.
The technical implementation of this vulnerability involves the manipulation of HTML element attributes within Markdown hyperlink syntax to create malicious DOM structures that interfere with JavaScript execution. When the vulnerable application processes Markdown content containing crafted hyperlinks, the improper validation allows HTML elements to be inserted into the DOM in positions that override or shadow native JavaScript functions. This creates a cascading failure scenario where critical JavaScript calls during application initialization fail due to the overwritten functions, resulting in complete application crashes or blank pages where the interface fails to render properly. The flaw is categorized under CWE-79 as a Cross-Site Scripting vulnerability, specifically manifesting as a DOM-based XSS attack that leverages DOM clobbering techniques. The attack requires no special privileges or authentication, making it particularly dangerous as it can be exploited through social engineering or by compromising user accounts with write access to Markdown-enabled fields.
The operational impact of CVE-2026-30235 extends beyond simple application disruption to potentially compromise the integrity of project data and user experience within OpenProject environments. When DOM clobbering occurs, it can cause complete application initialization failures, leaving users unable to access critical project management functionality. This vulnerability directly impacts the availability and reliability of the software, as users may encounter blank pages or complete application crashes when navigating to pages containing maliciously crafted Markdown content. The attack surface is broad since Markdown is commonly used throughout the application for issue descriptions, comments, and documentation, meaning that any user with the ability to submit Markdown content could potentially trigger this vulnerability. From an ATT&CK framework perspective, this vulnerability maps to T1211 - Exploitation for Defense Evasion and T1566 - Phishing, as it enables attackers to disrupt services and potentially gain further access to compromised systems through application-level attacks that bypass traditional network security controls.
Organizations utilizing OpenProject versions prior to 17.2.0 should immediately implement mitigation strategies to protect their systems from exploitation of this vulnerability. The primary and recommended remediation is the immediate upgrade to OpenProject version 17.2.0 or later, which includes proper input validation and sanitization of Markdown hyperlink content. Additionally, administrators should implement content filtering measures at the network level to restrict access to known malicious domains and monitor for suspicious Markdown content patterns. Security teams should also consider implementing web application firewalls with rules specifically targeting DOM clobbering attack patterns and establish monitoring procedures to detect unusual application behavior that may indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation in web applications and highlights how seemingly benign features like Markdown rendering can become attack vectors when inadequate security controls are in place, reinforcing the need for comprehensive security testing and validation of all user-provided content processing functionality.