Home

Description

webtransport-go is an implementation of the WebTransport protocol. From 0.3.0 to 0.9.0, an attacker can cause excessive memory consumption in webtransport-go's session implementation by sending a WT_CLOSE_SESSION capsule containing an excessively large Application Error Message. The implementation does not enforce the draft-mandated limit of 1024 bytes on this field, allowing a peer to send an arbitrarily large message payload that is fully read and stored in memory. This allows an attacker to consume an arbitrary amount of memory. The attacker must transmit the full payload to achieve the memory consumption, but the lack of any upper bound makes large-scale attacks feasible given sufficient bandwidth. This vulnerability is fixed in 0.10.0.

PUBLISHED Reserved 2025-12-29 | Published 2026-02-12 | Updated 2026-02-12 | Assigner GitHub_M




MEDIUM: 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Problem types

CWE-770: Allocation of Resources Without Limits or Throttling

Product status

< 0.10.0
affected

References

github.com/...ort-go/security/advisories/GHSA-g6x7-jq8p-6q9q

github.com/quic-go/webtransport-go/releases/tag/v0.10.0

cve.org (CVE-2026-21434)

nvd.nist.gov (CVE-2026-21434)

Download JSON