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TI-2026-17320 Aliases CVE-2026-21435GHSA-px4r-g4p3-hhqv

webtransport-go CloseWithError can block indefinitely

Priority LOW 39CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-400.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00465 40th percentileScored 2026-11-07
Fix Fixed webtransport-go (quic-go): 0.10.0github.com/quic-go/webtransport-go (Go): 0.10.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
quic-gowebtransport-gobefore 0.10.00.10.0Patch availableCNA
—github.com/quic-go/webtransport-go (Go)before 0.10.00.10.0Patch availableGHSA-px4r-g4p3-hhqv
  • webtransport-go Vendorquic-go Affected before 0.10.0 Fixed in 0.10.0 Patch available CNA
  • github.com/quic-go/webtransport-go (Go) Vendor— Affected before 0.10.0 Fixed in 0.10.0 Patch available GHSA-px4r-g4p3-hhqv

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:quic-go:webtransport-go:*:*:*:*:*:go:*:*before 0.10.0Vulnerablequic-go
  • cpe:2.3:a:quic-go:webtransport-go:*:*:*:*:*:go:*:* Versions before 0.10.0 Vulnerable ·quic-go

Remediation

  • Fix · CNA webtransport-go (quic-go) Fixed in 0.10.0
  • Fix · GHSA-px4r-g4p3-hhqv github.com/quic-go/webtransport-go (Go) Fixed in 0.10.0 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-21435
  2. 2026-10-03 Alias added: GHSA-px4r-g4p3-hhqv

References

Advisory 2

Other 2

  • TI-2026-17319 webtransport-go affected by Memory Exhaustion Attack due to Missing Length Check in WT_CLOSE_SESSION Capsule CVSS 3.1HIGH 7.5
  • TI-2026-17323 webtransport-go affected by a Memory Exhaustion Attack due to Missing Cleanup of Streams Map CVSS 3.1MEDIUM 5.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences