Executive brief
TinyMCE is a popular rich-text editor embedded in web applications. A cross-site scripting (XSS) vulnerability in its alert and confirm dialogs allows attackers to inject and execute arbitrary JavaScript in a user's browser when the editor displays error messages. This could lead to session hijacking, credential theft, or malware delivery, particularly affecting users of plugins like the image uploader that trigger these dialogs on errors.
Technical details
The vulnerability is a reflected XSS flaw in TinyMCE's alert and confirm dialogs (CWE-79). When these dialogs receive malicious HTML content—such as through error messages returned by plugins like the image upload handler—the HTML sanitization function fails to properly neutralize the input after unwrapping invalid elements, allowing arbitrary JavaScript execution. The attack requires network access, low privileges (user must be authenticated), and user interaction (the victim must trigger the dialog). The vulnerability affects TinyMCE versions prior to 5.10.7 (5.x branch) and 6.0.0–6.3.0 (6.x branch), and has been patched in TinyMCE 5.10.7 and 6.3.1.
Affected products
- Tiny Technologies TinyMCE before 5.10.7, 6.0.0 to 6.3.0
Timeline
- 2022-12-08: disclosed: Vulnerability published in GitHub Advisory Database
- 2022-12-08: patched: TinyMCE 5.10.7 and 6.3.1 released with patches