# 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.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Jul 2026
- **Updated:** 23 Jul 2026
- **Also known as:** GHSA-p9xj-3649-7qp8

## 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.

## Is CVE-2026-44909 being exploited?

There is no known exploitation of CVE-2026-44909 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44909 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-44909 in the wild and no public exploit code.

Affected product: Facebook proxygen. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-44909/ (Markdown: https://insights.sbomify.com/CVE-2026-44909/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44909
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44909
- OSV: https://osv.dev/vulnerability/CVE-2026-44909

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44909/
Summaries are generated and may contain mistakes; the official description above is the record.