---
id: "CVE-2026-119233"
page: "https://infrastack.ai/live/CVE-2026-119233"
kind: "vulnerability"
aliases: ["CVE-2026-119233"]
title: "proxygen: HTTP/3 frame buffering lets a remote peer exhaust memory and CPU"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: [{"name": "proxygen", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["c++", "http3", "proxygen", "runtime", "self-hosted"]
not_affected_if: ["no-http3", "not-proxygen"]
published_at: "2026-11-11T17:17:16+00:00"
first_seen_at: "2026-11-11T17:28:21+00:00"
updated_at: "2026-11-11T17:29:08+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119233", "first_seen_at": "2026-11-11T17:28:21+00:00"}]
exploit_sources: []
---

# proxygen: HTTP/3 frame buffering lets a remote peer exhaust memory and CPU

Link for people: https://infrastack.ai/live/CVE-2026-119233 (this .md is for agents)

Proxygen's HTTP/3 codec buffers incomplete non-DATA frames without a length limit and rescans them on each new fragment. A remote, unauthenticated HTTP/3 client can declare a huge frame and send it slowly, causing unbounded memory growth and quadratic CPU use that leads to denial of service.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:proxygen affected range not listed fixed no fixed version listed

## How to check

- Check whether your service uses proxygen (Meta's C++ HTTP library) with HTTP/3 enabled.
- Check the proxygen version in use against `v2026.11.09.00`.

## Fix

- proxygen: move to `v2026.11.09.00` or later.

## Timeline

- 2026-11-11T17:28:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119233

## Documents

- [fix] Patch: github.com https://github.com/meta/proxygen/commit/daf245bba7fe1304b9491403fe56f91153299781

## From the sources

proxygen's HTTP/3 codec buffered an incomplete non-DATA frame, such as a control-stream frame, a frame of an unknown or reserved type, or a HEADERS frame, until its entire declared length had arrived, without limiting that length, and re-scanned all buffered data each time more bytes arrived. A remote, unauthenticated HTTP/3 peer could declare a very large frame and deliver it slowly, causing unbounded memory growth and CPU usage that grows quadratically with the number of fragments, leading to denial of service. This issue affects proxygen versions prior to v2026.11.09.00.

---

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