CVE-2026-21438Network attack vector

Unauthenticated memory exhaustion via retained closed streams

Published Feb 12, 2026 · Updated Feb 12, 2026

Memory exhaustion in quic-go webtransport-go before 0.10.0 allows remote attackers to interrupt service by cycling WebTransport streams. The session maps retain closed unidirectional and bidirectional stream entries, so associated resources remain reachable and cannot be garbage-collected. No privileges or user interaction are required; repeated stream creation and closure drives steady memory growth and interrupts the hosting service.

CVSS severity5.3
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory exhaustion in quic-go webtransport-go before 0.10.0 allows remote attackers to interrupt service by cycling WebTransport streams. The session maps retain closed unidirectional and bidirectional stream entries, so associated resources remain reachable and cannot be garbage-collected. No privileges or user interaction are required; repeated stream creation and closure drives steady memory growth and interrupts the hosting service.

The record

CVE
CVE-2026-21438
Published
Feb 12, 2026
Updated
Feb 12, 2026
Vendor
quic-go
Product
webtransport-go
Classifications
CWE-401, CWE-459, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.10.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

quic-go · webtransport-goversion=< 0.10.0

Published CVSS scores

5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
CWE-459Incomplete Cleanup
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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