CVE-2019-9518 Some HTTP/2 implementations are vulnerable to a flood of empty frames, potentially leading to a denial of service
Attackers can cause denial of service by flooding HTTP/2 servers with empty frames, consuming excessive CPU 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-2019-9518?
CVE-2019-9518 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 a flood of empty frames, potentially leading to a denial of service. The attacker sends a stream of frames with an empty payload and without the end-of-stream flag. These frames can be DATA, HEADERS, CONTINUATION and/or PUSH_PROMISE. The peer spends time processing each frame disproportionate to attack bandwidth. This can consume excess CPU.
Which versions are affected by CVE-2019-9518?
It affects 18 products.
Products include Apache Traffic Server, Apple Swiftnio, Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Mcafee Web Gateway and 12 more.
How do I fix CVE-2019-9518?
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-2019-9518 being exploited?
There is no known exploitation of CVE-2019-9518 in the wild and no public exploit code.
Other vulnerabilities in Apache Traffic Server
Sources
Also known as ALPINE-CVE-2019-9518, CLEANSTART-2026-BZ30025, CLEANSTART-2026-WZ77365, CVE-2019-14992, DEBIAN-CVE-2019-9518, GHSA-93p3-5r25-4p75 and 1 more.