---
id: "CVE-2026-119235"
page: "https://infrastack.ai/live/CVE-2026-119235"
kind: "vulnerability"
aliases: ["CVE-2026-119235"]
title: "proxygen: unbounded QPACK literal buffering lets a remote peer exhaust memory"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["c++", "http3", "package", "proxygen"]
not_affected_if: ["no-http3-listener", "pinned-patched-version"]
published_at: "2026-11-11T17:17:16+00:00"
first_seen_at: "2026-11-11T17:28:21+00:00"
updated_at: "2026-11-11T17:29:05+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119235", "first_seen_at": "2026-11-11T17:28:21+00:00"}]
exploit_sources: []
---

# proxygen: unbounded QPACK literal buffering lets a remote peer exhaust memory

Link for people: https://infrastack.ai/live/CVE-2026-119235 (this .md is for agents)

Facebook's proxygen HTTP/3 library buffers an oversized QPACK string literal sent on the encoder stream without enforcing its size limit until the whole literal arrives. An unauthenticated remote peer can keep a connection sending data and exhaust server memory, causing denial of service.

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

## How to check

- Check the proxygen version in your build manifest or lockfile; affected if below `v2026.11.09.00`.
- Confirm whether your service serves HTTP/3 with proxygen, since the flaw is in its QPACK decoder.

## Fix

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

## Timeline

- 2026-11-11T17:28:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119235

## Documents

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

## From the sources

proxygen's QPACK decoder enforced its size limit on a string literal in an encoder-stream instruction only after the entire literal had been received. A remote, unauthenticated HTTP/3 peer could send an insert instruction on the QPACK encoder stream that declares an arbitrarily large literal and then keep sending data, causing the decoder to buffer it without bound for the lifetime of the connection and exhaust memory, leading to denial of service. The issue occurs regardless of the advertised QPACK dynamic table capacity, including when the dynamic table is disabled. This issue affects proxygen versions prior to v2026.11.09.00.

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_