🛡️ CVE-2026-21438 — webtransport-go

🟡 CVSS 5.3 — Medium ✅ No Known Exploit CWE-401 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

webtransport-go: Memory Exhaustion Attack due to Missing Cleanup of Streams Map

Summary

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.

Details

webtransport-go maintains an internal map tracking WebTransport streams (both unidirectional and bidirectional) belonging to a session. In affected versions, entries for closed streams were not removed from this map, causing the map to grow indefinitely as streams were created and closed.

A malicious peer can exploit this by opening large numbers of streams and closing them, leading to steady memory growth proportional to the number of closed streams.

The Fix

webtransport-go now removes closed streams from the internal map upon closure. This allows the associated resources to be garbage collected, bounding memory usage to active streams only.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability low.

Weakness class

CVE-2026-21438 is classified as CWE-401: Memory Leak. Allocated memory is never released, so long-running or repeated operations gradually exhaust it.

Affected software

CVE-2026-21438 is recorded against 2 packages.

  • github.com/quic-go/webtransport-go
  • webtransport-go (fixed in 0.10.0)

Timeline and source

Published on 12 February 2026 and last revised on 23 February 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Package)
github.com (Web)

Details

Severity Medium
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE CWE-401
Public Exploit ✅ No
Source NVD
Published 2026-02-12
Updated 2026-08-12
Modified 2026-02-23
Fix URL N/A

Affected Packages

Software From version Fixed in
github.com/quic-go/webtransport-go — —
webtransport-go — 0.10.0

Similar Threats

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