Home Cyber Security News Zero-Day Vulnerability In Pulse Secure VPN Went Under Attack

Zero-Day Vulnerability In Pulse Secure VPN Went Under Attack

by Abeerah Hashim
Pulse Secure VPN Zero-Day vulnerability

A serious security flaw existed in the Pulse Connect Secure SSL VPN appliance. The flaw, a zero-day vulnerability, was found to be under attack before Pulse Secure could deploy a fix for the VPN appliance.

Pulse Secure VPN Zero-Day Vulnerability

In a recent post, Pulse Secure has disclosed details about a zero-day vulnerability in the PSC VPN appliance.

As revealed, they spotted active exploitation of a new vulnerability in the Pulse Connect Secure (PCS) appliances against some customers.

This vulnerability, CVE-2021-22893, had received a critical severity rating with a CVSS score of 10.0. As elaborated in an advisory, a multiple use after free flaw could allow an attacker for remote code execution attacks.

Multiple use after free in Pulse Connect Secure before 9.1R11.4 allows a remote unauthenticated attacker to execute arbitrary code via license server web services.

This bug affected “PCS 9.0R3/9.1R1 and Higher” as the advisory confirms.

Researchers from FireEye have also elaborated on this zero-day in their report.

Together with this zero-day, Pulse Secure also confirmed the existence of three more vulnerabilities. These include two critical severity flaws leading to remote code execution by an authenticated attacker. These include CVE-2021-22894 – a buffer overflow exploitable via malicious meeting room, and CVE-2021-22899 – a command injection flaw exploitable via Windows File Resource Profiles. Both the bugs have received a CVSS score of 9.9.

Besides, they have also disclosed a high-severity vulnerability CVE-2021-22900 that received a CVSS of 7.2. This file write flaw also allowed an authenticated attacker to upload malicious archives in the admin web interface.

Patches Deployed – Update Now

Pulse Secure has fixed all four of these vulnerabilities with the release of Pulse Connect Secure 9.1R11.4.

Given the active exploitation of the flaw, the vendors and the researchers urge everyone to update the systems immediately.

Also, the US CISA has issued an emergency alert about this vulnerability.

Let us know your thoughts in the comments.

You may also like

Latest Hacking News

Privacy Preference Center


The __cfduid cookie is used to identify individual clients behind a shared IP address and apply security settings on a per-client basis.

cookie_notice_accepted and gdpr[allowed_cookies] are used to identify the choices made from the user regarding cookie consent.

For example, if a visitor is in a coffee shop where there may be several infected machines, but the specific visitor's machine is trusted (for example, because they completed a challenge within your Challenge Passage period), the cookie allows Cloudflare to identify that client and not challenge them again. It does not correspond to any user ID in your web application, and does not store any personally identifiable information.

__cfduid, cookie_notice_accepted, gdpr[allowed_cookies]


DoubleClick by Google refers to the DoubleClick Digital Marketing platform which is a separate division within Google. This is Google’s most advanced advertising tools set, which includes five interconnected platform components.

DoubleClick Campaign Manager: the ad-serving platform, called an Ad Server, that delivers ads to your customers and measures all online advertising, even across screens and channels.

DoubleClick Bid Manager – the programmatic bidding platform for bidding on high-quality ad inventory from more than 47 ad marketplaces including Google Display Network.

DoubleClick Ad Exchange: the world’s largest ad marketplace for purchasing display, video, mobile, Search and even Facebook inventory.

DoubleClick Search: is more powerful than AdWords and used for purchasing search ads across Google, Yahoo, and Bing.

DoubleClick Creative Solutions: for designing, delivering and measuring rich media (video) ads, interactive and expandable ads.



The _ga is asssociated with Google Universal Analytics - which is a significant update to Google's more commonly used analytics service. This cookie is used to distinguish unique users by assigning a randomly generated number as a client identifier. It is included in each page request in a site and used to calculate visitor, session and campaign data for the sites analytics reports. By default it is set to expire after 2 years, although this is customisable by website owners.

The _gat global object is used to create and retrieve tracker objects, from which all other methods are invoked. Therefore the methods in this list should be run only off a tracker object created using the _gat global variable. All other methods should be called using the _gaq global object for asynchronous tracking.

_gid works as a user navigates between web pages, they can use the gtag.js tagging library to record information about the page the user has seen (for example, the page's URL) in Google Analytics. The gtag.js tagging library uses HTTP Cookies to "remember" the user's previous interactions with the web pages.

_ga, _gat, _gid