---
id: "CVE-2026-115482"
kind: "vulnerability"
aliases: ["CVE-2026-115482"]
title: "lsquic HTTP/3: unbounded buffered header sets exhaust server memory"
severity: "high"
cvss: 7.5
epss: 0.00446
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["http3", "lsquic", "package", "quic", "self-hosted"]
not_affected_if: ["behind-proxy", "no-http3"]
published_at: "2026-10-22T16:17:35+00:00"
first_seen_at: "2026-10-23T21:57:31+00:00"
updated_at: "2026-10-25T03:15:10+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115482", "first_seen_at": "2026-10-23T21:57:31+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-115482", "first_seen_at": "2026-10-24T07:15:51+00:00"}]
---

# lsquic HTTP/3: unbounded buffered header sets exhaust server memory

lsquic, a QUIC and HTTP/3 library, does not limit how many header sets it buffers, so a peer can send QPACK data that makes it use excessive memory. An attacker can exhaust memory on a server or client that speaks HTTP/3 through lsquic, causing denial of service.

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

## How to check

- Find lsquic in your dependencies or build, for example `grep -ri lsquic` in vendored code or your package lock.
- Check the installed lsquic version against `4.9.0`; anything earlier is affected.

## Fix

- Upgrade lsquic to `4.9.0` or later.
- Until upgraded, limit HTTP/3 exposure or put a memory limit on the process running it.

## Timeline

- 2026-10-23T21:57:31+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115482
- 2026-10-24T07:15:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-115482

## From the sources

In lsquic before 4.9.0, the HTTP/3 implementation can use an excessive amount of memory because the number of buffered header sets is not limited, as demonstrated by a QPACK amplification attack. This is related to header_out_dynamic_entry and es_max_header_list_size.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_