CVE-2020-17480

Vulnerability

Description

A cross-site scripting (XSS) vulnerability exists in TinyMCE versions prior to 4.9.7 and 5.1.4. The flaw affects the core parser, the paste plugin, and the visualchars plugin, allowing arbitrary JavaScript execution when specially crafted content is inserted into the editor [1][4]. The root cause lies in insufficient sanitization and parser logic that fails to properly handle HTML-like text or malformed content [3][4].

Exploitation

An attacker can trigger the vulnerability by using the clipboard or application programming interfaces (APIs) to insert content into a TinyMCE editor instance [1][4]. No user interaction beyond normal editing actions is required; the malicious payload is executed when the editor processes the inserted content. The attack surface includes any web application that embeds an affected TinyMCE version and allows user input through copy-paste or programmatic insertion [2][4].

Impact

Successful exploitation enables arbitrary JavaScript execution in the context of the user's browser session. This can lead to data theft, session hijacking, defacement, or further attacks against the application's users [1][4].

Mitigation

TinyMCE 4.9.7 and 5.1.4 fully patch the vulnerability by improving parser logic and HTML sanitization [3][4]. As workarounds, administrators can disable the impacted plugins (paste, visualchars) or manually sanitize content using the BeforeSetContent event [4]. Upgrade is strongly recommended.