CVE-2026-44909
Proxygen HTTP/2 Flow Control Denial of Service Vulnerability
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.
INFO
Published Date :
July 23, 2026, 5:16 p.m.
Last Modified :
July 23, 2026, 5:50 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 4fc57720-52fe-4431-a0fb-3d2c8747b827 | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Proxygen to a fixed version.
- Implement generalized slow-consumer detection.
- Configure appropriate flow control limits.
- Monitor server resource utilization.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-44909.
| URL | Resource |
|---|---|
| https://github.com/facebook/proxygen/commit/f28742f21f7022c261b7620d4e6b20d82b6cff72 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-44909 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-44909
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-44909 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-44909 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jul. 23, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Facebook', 'product': 'proxygen', 'versions': [{'status': 'affected', 'version': 'v2017.01.16.00', 'lessThan': 'v2026.07.20.00', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added Reference https://github.com/facebook/proxygen/commit/f28742f21f7022c261b7620d4e6b20d82b6cff72