CVE-2019-9511 Denial of service in n/a
Attackers can cause denial of service in HTTP/2 servers by manipulating window sizes and stream priorities to exhaust CPU and memory resources.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2019-9511?
CVE-2019-9511 is a high-severity denial of service vulnerability in Apache Traffic Server, published on 13 Aug 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Some HTTP/2 implementations are vulnerable to window size manipulation and stream prioritization manipulation, potentially leading to a denial of service. The attacker requests a large amount of data from a specified resource over multiple streams. They manipulate window size and stream priority to force the server to queue the data in 1-byte chunks. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.
Which versions are affected by CVE-2019-9511?
It affects 20 products.
Products include Apache Traffic Server, Apple Swiftnio, Canonical Ubuntu Linux, Debian Debian Linux, F5 Nginx, Fedoraproject Fedora and 14 more.
How do I fix CVE-2019-9511?
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-2019-9511 being exploited?
There is no known exploitation of CVE-2019-9511 in the wild and no public exploit code.
Public exploit code: 2 proofs of concept on GitHub.
Other vulnerabilities in Apache Traffic Server
Sources
Also known as ALPINE-CVE-2019-9511, CLEANSTART-2024-IW99789, CLEANSTART-2026-BU08584, CLEANSTART-2026-LU76870, DEBIAN-CVE-2019-9511, GHSA-89fc-749h-w2fj and 1 more.