Quick answers
- Is CVE-2026-44909 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-44909 being exploited in the wild.
- How severe is CVE-2026-44909?
- High severity, with a CVSS score of 7.5, published 23 July 2026.
- Which products and versions are affected?
- Facebook Proxygen v2017.01.16.00 through v2026.07.20.00.
- Is there a fix for CVE-2026-44909?
- A patch was published on 2026-07-16: Fix committed to GitHub repository Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-44909 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-44909?
- Check whether you run Facebook Proxygen at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A vulnerability in Proxygen's core HTTP session layer stems from the lack of a generalized slow-consumer detection mechanism. A remote, unauthenticated attacker can exploit HTTP/2 flow-control by setting SETTINGS_INITIAL_WINDOW_SIZE to 0 or withholding WINDOW_UPDATE frames. This forces the server to buffer complete response bodies in memory indefinitely for stalled streams. By opening numerous simultaneous streams for large resources while preventing transmission, an attacker can cause unbounded memory growth, leading to resource exhaustion and denial of service (DoS). The fix introduces an edge-triggered slow-consumer detector in HTTPSessionBase that drops connections if pending writes exceed a defined threshold without sufficient forward progress.
Affected products
- Facebook Proxygen v2017.01.16.00 through v2026.07.20.00
Timeline
- 2026-07-16: patched: Fix committed to GitHub repository
- 2026-07-23: advisory: NVD advisory published