---
id: CVE-2026-57497
title: webtransport-go is an implementation of the WebTransport protocol
summary: >-
  webtransport-go is an implementation of the WebTransport protocol. Prior to
  0.11.1, Session.parseNextCapsule() in session.go skips an unknown WebTransport
  capsule on the HTTP/3 request stream by calling io.ReadAll on the capsule
  reader, …
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-770
vendor: quic-go
product: webtransport-go
affected:
  - webtransport-go < 0.11.1
patched:
  - github.com/quic-go/webtransport-go 0.11.1
published: '2026-09-14'
updated: '2026-09-14'
sourceUpdated: '2026-09-14T20:16:48.567'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-57497'
references:
  - url: >-
      https://github.com/quic-go/webtransport-go/commit/3aecd11736579530ff067651c30a543eb0b4b8c4
    label: security-advisories@github.com
  - url: 'https://github.com/quic-go/webtransport-go/pull/290'
    label: security-advisories@github.com
  - url: 'https://github.com/quic-go/webtransport-go/releases/tag/v0.11.1'
    label: security-advisories@github.com
  - url: >-
      https://github.com/quic-go/webtransport-go/security/advisories/GHSA-g35j-m5xg-vh3q
    label: security-advisories@github.com
  - url: 'https://github.com/advisories/GHSA-g35j-m5xg-vh3q'
tags:
  - nvd
  - cve.org
  - ghsa
  - go
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-14T19:22:14.262426Z'
aliases:
  - GHSA-g35j-m5xg-vh3q
ecosystem: go
ingestedAt: '2026-07-24T21:39:14.858Z'
epss: 0.00524
epssPercentile: 0.41922
---

## Overview

webtransport-go is an implementation of the WebTransport protocol. Prior to 0.11.1, Session.parseNextCapsule() in session.go skips an unknown WebTransport capsule on the HTTP/3 request stream by calling io.ReadAll on the capsule reader, retaining the complete declared capsule body in memory. A malicious peer can send a large unknown capsule and cause a client or server to allocate memory for the full payload; QUIC flow control does not bound the total retained allocation because reading advances the flow-control window while the received bytes remain in memory. The resulting memory and resource exhaustion can disrupt or crash the affected process. This issue is fixed in version 0.11.1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-57497)

Affected packages:

- `github.com/quic-go/webtransport-go <= 0.11.0`

Patched in:

- `github.com/quic-go/webtransport-go 0.11.1`

Source: https://github.com/advisories/GHSA-g35j-m5xg-vh3q