VulnerabilityAnalyzed

CVE-2026-21438

Prior to 0.10.0, an attacker can cause unbounded memory consumption repeatedly creating and closing many WebTransport streams.

MEDIUM 5.3EPSS 0.38%

Does this matter?

Lower severity and a low EPSS score (0.38%). Track it; it rarely justifies an emergency change on its own.

Description

webtransport-go is an implementation of the WebTransport protocol. Prior to 0.10.0, an attacker can cause unbounded memory consumption repeatedly creating and closing many WebTransport streams. Closed streams were not removed from an internal session map, preventing garbage collection of their resources. This vulnerability is fixed in v0.10.0.

CVSS 3.1: 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS: 0.38% probability · 31th percentile
CISA KEV: Not listed
Weakness: CWE-401, CWE-459
Affected: quic-go/webtransport-go
Source: security-advisories@github.com

References

https://github.com/quic-go/webtransport-go/releases/tag/v0.10.0Product, Release Notes
https://github.com/quic-go/webtransport-go/security/advisories/GHSA-2f2x-8mwp-p2gcVendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.