CVE-2019-11479 Denial of service in Linux kernel
Remote attackers can cause denial of service by fragmenting TCP resend queues due to a hard-coded small MSS in the Linux kernel.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2019-11479?
CVE-2019-11479 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 18 Jun 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Jonathan Looney discovered that the Linux kernel default MSS is hard-coded to 48 bytes. This allows a remote peer to fragment TCP resend queues significantly more than if a larger MSS were enforced. A remote attacker could use this to cause a denial of service. This has been fixed in stable kernel releases 4.4.182, 4.9.182, 4.14.127, 4.19.52, 5.1.11, and is fixed in commits 967c05aee439e6e5d7d805e195b3a20ef5c433d6 and 5f3e2bf008c2221478101ee72f5cb4654b9fc363.
Which versions are affected by CVE-2019-11479?
It affects 21 products.
Products include Canonical Ubuntu Linux, F5 Big-Ip Access Policy Manager, F5 Big-Ip Advanced Firewall Manager, F5 Big-Ip Analytics, F5 Big-Ip Application Acceleration Manager, F5 Big-Ip Application Security Manager and 15 more.
How do I fix CVE-2019-11479?
Apply the vendor's patch.
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-2019-11479 being exploited?
There is no known exploitation of CVE-2019-11479 in the wild and no public exploit code.
Other vulnerabilities in Canonical Ubuntu Linux
Sources
Also known as DEBIAN-CVE-2019-11479, GHSA-99cq-xr7g-h22w, UBUNTU-CVE-2019-11479, USN-4041-1, USN-4041-2.