CVE-2020-7937

Vulnerability

Overview

CVE-2020-7937 is a stored cross-site scripting (XSS) vulnerability in the Plone content management system, affecting versions 5.0 through 5.2.1. The flaw resides in the title field of Plone content objects, where a user with specific privileges (e.g., those able to create or edit content) can insert arbitrary JavaScript. This script is then stored on the server and executed in the browser of any other user who accesses that site, effectively allowing privilege escalation and malicious actions on behalf of the victim [1].

Attack

Vector and Exploitation

To exploit this vulnerability, an attacker must have a user account with the appropriate permission level to modify the title field of published content. The official description confirms that only users with a “certain privilege level” can inject the payload [1]. Once the title is saved with the embedded script, the XSS payload becomes part of the site’s persistent content. The attacker does not need to trick a user into clicking a direct link; the script will fire automatically when other users navigate to the page containing the tainted title [2].

Impact and

Risk

Successful exploitation allows the attacker to execute arbitrary JavaScript in the context of the Plone site. This can lead to session hijacking, theft of sensitive data (such as authentication tokens or CSRF tokens), defacement, or further internal attacks against users of the CMS. Because Plone is used in both public-facing websites and internal intranets, the impact may extend to unauthenticated visitors or authenticated users with higher privileges [3]. The vulnerability is particularly concerning because the title field is a standard and commonly displayed piece of content.

Mitigation and

Remediation

The Plone project released a security hotfix on 2020-01-21 that addresses CVE-2020-7937 among other issues [3]. Administrators are strongly advised to apply the hotfix immediately or upgrade to a patched version. For Plone 5.x, the fix should be applied to versions 5.2.1 and below; Plone 4.x users are also encouraged to update. The advisory notes that earlier unsupported versions might be affected, though they have not been tested [3][4]. No mention of the vulnerability being listed in CISA’s Known Exploited Vulnerabilities (KEV) catalog has been made.