CVE-2026-21435— webtransport-go CloseWithError can block indefinitely
Quick assessment
Affected
quic-go webtransport-go
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
webtransport-go是quic-go开源的一个Go语言库。 webtransport-go 0.10.0之前版本存在资源管理错误漏洞，该漏洞源于恶意对等方可能阻止或无限期延迟会话关闭，可能导致拒绝服务。
Possible ATT&CK Techniques 1 AI
T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-21435
Vulnerability Information
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Vulnerability Title
webtransport-go CloseWithError can block indefinitely
Source: CVE Program / CVE List V5
Vulnerability Description
webtransport-go is an implementation of the WebTransport protocol. Prior to v0.10.0, an attacker can cause a denial of service in webtransport-go by preventing or indefinitely delaying WebTransport session closure. A malicious peer can withhold QUIC flow control credit on the CONNECT stream, blocking transmission of the WT_CLOSE_SESSION capsule and causing the close operation to hang. This vulnerability is fixed in v0.10.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
webtransport-go 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
webtransport-go是quic-go开源的一个Go语言库。 webtransport-go 0.10.0之前版本存在资源管理错误漏洞，该漏洞源于恶意对等方可能阻止或无限期延迟会话关闭，可能导致拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| quic-go | webtransport-go | < 0.10.0 | - |
|
II. Public POCs for CVE-2026-21435
| # | POC Description | Source Link | Shenlong Link |
|---|
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Vendor Advisories for CVE-2026-21435 (1)
Same Patch Batch · quic-go · 2026-02-12 · 3 CVEs total
| CVE-2026-21434 | 5.3 MEDIUM | webtransport-go affected by Memory Exhaustion Attack due to Missing Length Check in WT_CLO |
| CVE-2026-21438 | 5.3 MEDIUM | webtransport-go affected by a Memory Exhaustion Attack due to Missing Cleanup of Streams M |
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V. Comments for CVE-2026-21435
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