Vulnerability · Published Feb 12, 2026 · Assigned by GitHub_M

CVE-2026-21438webtransport-go affected by a Memory Exhaustion Attack due to Missing Cleanup of Streams Map

Medium 5.3

In plain English

A medium-severity memory leak in webtransport-go from quic-go. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.4%top 64.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/quic-go/webtransport-go	0.10.0	GHSA-2f2x-8mwp-p2gc
Go	github.com/quic-go/webtransport-go	0.10.0	GO-2026-4483

Affected products (as reported)

Vendor	Product	Versions
quic-go	webtransport-go	< 0.10.0

Weakness: CWE-401, CWE-459 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

https://github.com/quic-go/webtransport-go/security/advisories/GHSA-2f2x-8mwp-p2gc x_refsource_CONFIRM
https://github.com/quic-go/webtransport-go/releases/tag/v0.10.0 x_refsource_MISC