CVE-2026-57497

MEDIUM 5.3

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

CVSS Score

5.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-770
Vendor	quic-go
Product	webtransport-go
Published	Sep 14, 2026
Last Updated	Sep 14, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

Affected Versions

quic-go / webtransport-go

< 0.11.1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/quic-go/webtransport-go/security/advisories/GHSA-g35j-m5xg-vh3q github.com: https://github.com/quic-go/webtransport-go/pull/290 github.com: https://github.com/quic-go/webtransport-go/commit/3aecd11736579530ff067651c30a543eb0b4b8c4 github.com: https://github.com/quic-go/webtransport-go/releases/tag/v0.11.1