jQuery Object.prototype Pollution Cross-Site Scripting Vulnerability [CVE-2019-11358]

CVE Number – CVE-2019-11358

A vulnerability in jQuery as used in multiple products could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack on a targeted system.

The vulnerability exists because the affected software mishandles the jQuery.extend(true, {}, …)function and is due to Object.prototype pollution. An attacker could exploit this vulnerability by persuading a user to access a link that submits malicious input containing an enumerable __proto__property to the targeted system. A successful exploit could extend the native Object.prototype, which the attacker could use to conduct a XSS attack. 

Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available. 

jQuery has confirmed the vulnerability and released software updates.


  • To exploit this vulnerability, the attacker may use misleading language or instructions to persuade a user to access a link that submits malicious input to the targeted system.


  • Administrators are advised to apply the appropriate updates.

    Administrators are advised to allow only trusted users to have network access.

    Administrators are advised to use an unprivileged account when browsing the Internet.

    Administrators are advised to monitor critical systems.

    Users are advised not to open email messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in email messages are safe, they are advised not to open them.

    Users are advised not to visit websites or follow links that have suspicious characteristics or cannot be verified as safe.

Vendor Announcements

Fixed Software

  • jQuery has released software updates at the following link: jQuery 3.4.0

    Drupal.org has released software updates at the following links: Drupal, and 7.66

Jason Davies

UK based technology professional, with an interest in computer security and telecoms.

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