CVE-2026-104078 in Obsidian
Summary
by MITRE • 10/08/2026
Obsidian Desktop before 1.14.0 contains a filter bypass vulnerability in the bundled MathJax 3.2.2 Safe component that allows attackers to execute arbitrary code by embedding a crafted \href value with a TAB byte in the URL scheme, causing filterURL to produce an empty protocol that bypasses the configured safeProtocols restrictions. Attackers can craft a note containing a malicious MathJax formula that renders as a javascript: URL anchor, which when clicked by the victim in Live Preview executes in the Node-integration-enabled vault renderer via require('child_process'), achieving arbitrary operating system command execution as the desktop user.
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Analysis
by VulDB Data Team • 10/08/2026
The vulnerability identified in Obsidian Desktop versions prior to 1.14.0 stems from a critical flaw within the bundled MathJax library, specifically version 3.2.2 Safe component. This security issue is classified under CWE-79 as an improper neutralization of input during web page generation, commonly known as cross-site scripting, but with escalated consequences due to the application's architecture. The core technical deficiency lies in the filterURL function responsible for sanitizing URLs within mathematical formulas rendered by MathJax. When processing hyperlinks defined via LaTeX commands such as \href, the filtering logic fails to adequately handle specific control characters embedded within the URL scheme. Specifically, an attacker can exploit this weakness by inserting a TAB byte into the protocol portion of the link definition. This manipulation causes the sanitization routine to incorrectly parse or strip the protocol identifier entirely, resulting in an empty string for the protocol field rather than rejecting the input as invalid.
This bypass mechanism allows malicious actors to circumvent the configured safeProtocols restrictions that are designed to prevent the execution of dangerous schemes like javascript: within the application's renderer. By exploiting this parsing error, an attacker can craft a MathJax formula where the sanitized output effectively mimics a valid link structure while secretly carrying a javascript: scheme intent. When such a crafted note is opened in Live Preview mode, which utilizes Electron's webview for rendering content with Node.js integration enabled by default or via specific vault configurations, the malicious anchor tag becomes active. The vulnerability does not require user interaction beyond viewing the rendered formula if auto-execution features are present, but typically requires the victim to click on the crafted link element within the preview pane to trigger the payload execution context.
The operational impact of this vulnerability is severe, leading directly to arbitrary operating system command execution with the privileges of the desktop application's user account. Once the javascript: URL anchor is activated in the Node-integration-enabled renderer, it gains access to Electron's internal APIs. The attacker can leverage these capabilities by invoking require('child_process') within the JavaScript context generated by the malicious formula. This allows for the spawning of arbitrary processes on the host machine, effectively granting full control over the victim's system without any sandbox restrictions that would normally apply in a standard web browser environment. This represents a significant escalation from typical cross-site scripting vulnerabilities because it bridges the gap between client-side script execution and native OS-level command injection due to the desktop application's architecture.
From an industry standards perspective, this vulnerability aligns with MITRE ATT&CK technique T1059 Command and Scripting Interpreter, specifically through JavaScript usage in a desktop environment context. It also relates to CWE-284 Improper Access Control regarding the bypass of security restrictions on URL schemes. The flaw highlights the risks associated with bundling third-party rendering libraries that may not be fully hardened against edge-case input manipulations within applications that maintain Node.js integration for extended functionality. Mitigation strategies primarily involve updating Obsidian Desktop to version 1.14.0 or later, where this parsing logic has been corrected to properly reject inputs containing control characters in the protocol field and enforce strict validation of URL schemes before rendering. For environments unable to update immediately, disabling Live Preview's Node integration for untrusted vaults or restricting the use of complex MathJax formulas from unknown sources can reduce exposure risk until a patch is applied.