WordPress Discovers XSS Vulnerability – Recommends Updating To 6.5.2

WordPress announced the 6.5.2 Maintenance and Security Release update that patches a store cross site scripting vulnerability and fixes over a dozen bugs in the core and the block editor.

The same vulnerability affects both the WordPress core and the Gutenberg plugin.

Cross Site Scripting (XSS)

An XSS vulnerability was discovered in WordPress that could allow an attacker to inject scripts into a website that then attacks site visitors to those pages.

There are three kinds of XSS vulnerabilities but the most commonly discovered in WordPress plugins, themes and WordPress itself are reflected XSS and stored XSS.

Reflected XSS requires a victim to click a link, an extra step that makes this kind of attack harder to launch.

A stored XSS is the more worrisome variant because it exploits a flaw that allows the attacker to upload a script into the vulnerable site that can then launch attacks against site visitors. The vulnerability discovered in WordPress is a stored XSS.

The threat itself is mitigated to a certain degree because this is an authenticated stored XSS, which means that the attacker needs to first acquire at least a contributor level permissions in order to exploit the website flaw that makes the vulnerability possible.

This vulnerability is rated as a medium level threat, receiving a Common Vulnerability Scoring System (CVSS) score of 6.4 on a scale of 1 – 10.

Wordfence describes the vulnerability:

“WordPress Core is vulnerable to Stored Cross-Site Scripting via user display names in the Avatar block in various versions up to 6.5.2 due to insufficient output escaping on the display name. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.”

WordPress.org Recommends Updating Immediately

The official WordPress announcement recommended that users update their installations, writing:

“Because this is a security release, it is recommended that you update your sites immediately. Backports are also available for other major WordPress releases, 6.1 and later.”

Read the Wordfence advisories:

WordPress Core < 6.5.2 – Authenticated (Contributor+) Stored Cross-Site Scripting via Avatar Block

Gutenberg 12.9.0 – 18.0.0 – Authenticated (Contributor+) Stored Cross-Site Scripting via Avatar Block

Read the official WordPress.org announcement:

WordPress 6.5.2 Maintenance and Security Release

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