CVE-2019-1029 Skype for Business and Lync Server Denial of Service Vulnerability

Medium 5.9 Published 12 Jun 2019 Updated 20 May 2025

An attacker can cause Skype for Business servers to stop responding by initiating rapid calls via a dial-in link.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2019-1029?

CVE-2019-1029 is a medium-severity denial of service vulnerability in Microsoft Lync Server 2010, published on 12 Jun 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A denial of service vulnerability exists in Skype for Business. An attacker who successfully exploited the vulnerability could cause Skype for Business to stop responding. Note that the denial of service would not allow an attacker to execute code or to elevate the attacker's user rights. To exploit the vulnerability, an attacker needs to obtain a dial-in link for a vulnerable server and then initiates a series of calls within a short amount of time. The update addresses the vulnerability by correcting the way that Skype for Business server handles objects in memory.

Which versions are affected by CVE-2019-1029?

It affects 1 product.

Products include Microsoft Lync Server.

How do I fix CVE-2019-1029?

No fix has been published for CVE-2019-1029 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2019-1029 being exploited?

There is no known exploitation of CVE-2019-1029 in the wild and no public exploit code.

Sources

Also known as GHSA-6m2x-7chh-x75q.