Description

Trilium Notes, version v0.103.0 and earlier, contains a stored cross-site scripting (XSS) vulnerability in the share renderer for webView notes due to improper HTML escaping of user-controlled #webViewSrc values. This vulnerability allows attackers with note-authoring privileges to inject arbitrary JavaScript that executes for any user who opens the shared note, including administrators.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.4",
  "pubDate": "2026-09-14T18:20:29.467Z",
  "pubdate": "2026-09-14T18:20:29.467Z",
  "executiveSummary": "Trilium Notes version v0.103.0 and earlier is susceptible to a stored cross-site scripting (XSS) vulnerability residing within the share renderer for webView notes.\nThe vulnerability arises from insufficient sanitization of the #webViewSrc attribute, enabling an authenticated attacker with note-authoring privileges to inject arbitrary, malicious JavaScript payloads into the note content.\nWhen a victim, including users with administrative privileges, accesses the crafted shared note, the injected script executes within the context of the user's session.\nThis vulnerability poses a significant security risk, as successful exploitation facilitates unauthorized access to sensitive user data, potential session hijacking, and the execution of arbitrary actions on behalf of the victim within the Trilium Notes application.\nThe exploit requires the attacker to have sufficient permissions to create or modify notes, which are then rendered through the vulnerable webView component.",
  "technicalDetails": "The root cause of the vulnerability is improper HTML escaping of user-controllable input within the #webViewSrc value processed by the share renderer.\nIn Trilium Notes, the webView component is designed to render external content, yet the application fails to adequately validate or encode the URI or data provided to the #webViewSrc attribute before injecting it into the Document Object Model (DOM).\nAn attacker with note-authoring privileges can craft a note containing a malicious #webViewSrc value. By leveraging URI schemes that support JavaScript execution (such as 'javascript:' pseudo-protocols) or by injecting event handlers if the rendering logic is susceptible to attribute breakout, the attacker bypasses intended input constraints.\nThe attack flow proceeds as follows: First, the attacker embeds the malicious payload into the note configuration. Second, the note is shared or accessed by a target user. Third, the Trilium Notes share renderer processes the note and insecurely embeds the attacker-supplied #webViewSrc string into the rendered HTML page. Finally, when the victim's browser parses the page, it executes the injected JavaScript.\nBecause the execution occurs within the security context of the victim's authenticated session, the malicious script inherits the victim's access level. If an administrator views the note, the script operates with administrative privileges, potentially leading to unauthorized data exfiltration, modification of application settings, or the creation of new administrative accounts.\nThe vulnerability is restricted to the note-authoring subsystem but is effectively stored in the database, ensuring persistent execution whenever the note is rendered. No specific network-level exploitation is required beyond access to the Trilium Notes interface, making this a high-impact persistent threat within the application environment.\nThe vulnerability specifically affects the webView rendering component, which handles the display of note content. The failure to apply context-aware output encoding ensures that the browser interprets the input as executable code rather than plain text or a safe resource locator."
}