Good news. Citrix delivers first patches to mop up Shitrix flaw that is being actively exploited

Graham Cluley
Graham Cluley
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Good news. Citrix delivers first patches to mop up Shitrix flaw

Over the weekend Citrix announced that its plans to release patches for critical vulnerabilities in its technology, used by tens of thousands of businesses worldwide, have significantly sped up.

The first patches, which address the CVE-2019-19781 or so-called Shitrix vulnerability, are now available for versions 11.1 and 12.0 of Citrix Application Delivery Controller (ADC), formerly known as NetScaler ADC.

“We urge customers to immediately install these fixes,” Citrix says.

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Furthermore the company has moved forward its target dates for release of permanent patches for other versions of ADC and older versions of the Citrix SD-WAN WANOP.

That’s certainly good news as hackers have been actively exploiting the flaw – in some cases even using it to compromise vulnerable systems, remove malware planted by earlier hackers, and applying Citrix’s mitigation steps – only to leave a secret backdoor open for future compromise.

Of course, if you’re still waiting for patches from Citrix for your company’s particular setup you would be wise to still follow their mitigation advice as soon as possible.


Graham Cluley is an award-winning keynote speaker who has given presentations around the world about cybersecurity, hackers, and online privacy. A veteran of the computer security industry since the early 1990s, he wrote the first ever version of Dr Solomon's Anti-Virus Toolkit for Windows, makes regular media appearances, and is the co-host of the popular "The AI Fix" and "Smashing Security" podcasts. Follow him on Bluesky and Mastodon, or drop him an email.

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