CVE-2026-44909 Denial of service in proxygen
Remote attackers can cause denial of service in Proxygen by exploiting HTTP/2 flow control to induce unbounded memory growth.
- 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-2026-44909?
CVE-2026-44909 is a high-severity denial of service vulnerability in Facebook proxygen, published on 23 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Proxygen lacked a generalized slow-consumer detection mechanism in its core HTTP session layer. A remote, unauthenticated attacker could exploit HTTP/2 flow-control by setting SETTINGS_INITIAL_WINDOW_SIZE to 0 or withholding WINDOW_UPDATE frames, causing the server to buffer complete response bodies in memory indefinitely for stalled streams. By opening many simultaneous streams requesting large resources while preventing the server from transmitting responses, an attacker could induce unbounded memory growth leading to service degradation, resource exhaustion, or denial of service. Versions v2017.01.16.00 through v2026.07.20.00 are affected.
Which versions are affected by CVE-2026-44909?
How do I fix CVE-2026-44909?
No fix has been published for CVE-2026-44909 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-2026-44909 being exploited?
There is no known exploitation of CVE-2026-44909 in the wild and no public exploit code.
Sources
Also known as GHSA-p9xj-3649-7qp8.