CVE-2019-9514 Some HTTP/2 implementations are vulnerable to a reset flood, potentially leading to a denial of service
Attackers can cause denial of service in HTTP/2 implementations by flooding streams with invalid requests, consuming excessive memory and 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-2019-9514?
CVE-2019-9514 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 reset flood, potentially leading to a denial of service. The attacker opens a number of streams and sends an invalid request over each stream that should solicit a stream of RST_STREAM frames from the peer. Depending on how the peer queues the RST_STREAM frames, this can consume excess memory, CPU, or both.
Which versions are affected by CVE-2019-9514?
5 open source packages ship an affected version, including h2. It affects 28 products.
| Package | Affected | Fixed in |
|---|---|---|
h2 crates.io | All versions | 0.3.24 |
h2 crates.io | All versions | 0.3.24 |
h2 crates.io | From 0.0.0-0 | 0.3.24, 0.4.2 |
h2 crates.io | From 0.4.0 | 0.4.2 |
h2 crates.io | From 0.4.0 | 0.4.2 |
Products include Apache Traffic Server, Apple Swiftnio, Canonical Ubuntu Linux, Debian Debian Linux, F5 Big-Ip Local Traffic Manager, Fedoraproject Fedora and 22 more.
How do I fix CVE-2019-9514?
Upgrade h2 to a fixed version for your release line: 0.3.24 or 0.4.2.
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-2019-9514 being exploited?
There is no known exploitation of CVE-2019-9514 in the wild and no public exploit code.
Other vulnerabilities in Apache Traffic Server
Sources
Also known as ALPINE-CVE-2019-9514, AZL-38389, CLEANSTART-2025-AF65508, CLEANSTART-2026-QQ59156, CLEANSTART-2026-YV80778, CVE-2019-14990 and 4 more.