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Drupal 8 Updated to Patch Flaw in WYSIWYG Editor

Updates released on Wednesday for Drupal 8 patch a moderately critical cross-site scripting (XSS) vulnerability affecting a third-party JavaScript library.

The flaw impacts CKEditor, a WYSIWYG HTML editor included in the Drupal core. CKEditor exposes users to XSS attacks due to a flaw in the Enhanced Image (image2) plugin.

"The vulnerability stemmed from the fact that it was possible to execute XSS inside CKEditor using the <img> tag and specially crafted HTML," said CKEditor developers. "Please note that the default presets (Basic/Standard/Full) do not include this plugin, so you are only at risk if you made a custom build and enabled this plugin." 

XSS flaws can typically be exploited by getting the targeted user to click on a specially crafted link, and they allow attackers to execute arbitrary code, leading to session hijacking, data theft or phishing.

The security hole, discovered by Kyaw Min Thein, affects CKEditor versions 4.5.11 through 4.9.1, and it has been fixed with the release of version 4.9.2. The patched version of CKEditor has been included in Drupal 8.5.2 and 8.4.7.

"The Drupal 7.x CKEditor contributed module is not affected if you are running CKEditor module 7.x-1.18 and using CKEditor from the CDN, since it currently uses a version of the CKEditor library that is not vulnerable," Drupal developers explained. "If you installed CKEditor in Drupal 7 using another method (for example with the WYSIWYG module or the CKEditor module with CKEditor locally) and you’re using a version of CKEditor from 4.5.11 up to 4.9.1, update the third-party JavaScript library by downloading CKEditor 4.9.2 from CKEditor's site."

This is the second Drupal security update in recent weeks. The previous update was released in late March and it addressed CVE-2018-7600, a highly critical remote code execution vulnerability that allows attackers to take control of impacted websites.

Dubbed Drupalgeddon2, the flaw has been exploited in the wild to deliver backdoors, cryptocurrency miners, and other types of malware. The first attempts to exploit the vulnerability were spotted in mid-April, shortly after technical details and proof-of-concept (PoC) code were made public.

Related: Flaw in Drupal Module Exposes 120,000 Sites to Attacks

Related: Several Vulnerabilities Patched in Drupal

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.