webtransport-go: Memory Exhaustion Attack due to Buffering of Unknown Capsules (CVE-2026-57497) | HOL Guard CVE

Medium · CVSS 5.3CVE-2026-57497GHSA-G35J-M5XG-VH3Q

webtransport-go: Memory Exhaustion Attack due to Buffering of Unknown Capsules

Answer in brief

CVE-2026-57497 records a Medium severity (CVSS 5.3) vulnerability in webtransport-go: Memory Exhaustion Attack due to Buffering of Unknown Capsules. The current sources do not mark it as known exploited. The current feed maps quic-go/webtransport-go (generic), github.com/quic-go/webtransport-go (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 14, 2026Updated Sep 14, 2026Source checked Sep 14, 2026First seen by HOL Aug 8, 2026Material review Sep 14, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps quic-go/webtransport-go (generic), github.com/quic-go/webtransport-go (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
quic-go/webtransport-gogeneric	< 0.11.1	Not reported
github.com/quic-go/webtransport-gogo	>=0 <0.11.1	0.11.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for quic-go/webtransport-go, github.com/quic-go/webtransport-go.
Review the reported fix. Update github.com/quic-go/webtransport-go to 0.11.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 14, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 14, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 8, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.