quic-go webtransport-go up to 0.9.x WT_CLOSE_SESSION resource consumption

CVSS Meta Temp Score
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CTI Interest Score
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6.0$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic was found in quic-go webtransport-go up to 0.9.x. This issue affects some unknown processing. Such manipulation of the argument WT_CLOSE_SESSION leads to resource consumption. This vulnerability is referenced as CVE-2026-21435. It is possible to launch the attack remotely. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in quic-go webtransport-go up to 0.9.x. Affected by this issue is an unknown function. The manipulation of the argument WT_CLOSE_SESSION with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-21435 since 12/29/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 0.10.0 eliminates this vulnerability. The upgrade is hosted for download at github.com.

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Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.0
VulDB Meta Temp Score: 6.0

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔒

CNA Base Score: 5.3
CNA Vector (GitHub_M): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Resource consumption
CWE: CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: webtransport-go 0.10.0

Timelineinfo

12/29/2025 CVE reserved
02/12/2026 +45 days Advisory disclosed
02/12/2026 +0 days VulDB entry created
02/20/2026 +8 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-px4r-g4p3-hhqv
Status: Confirmed

CVE: CVE-2026-21435 (🔒)
GCVE (CVE): GCVE-0-2026-21435
GCVE (VulDB): GCVE-100-345800

Entryinfo

Created: 02/12/2026 23:46
Updated: 02/20/2026 19:34
Changes: 02/12/2026 23:46 (66), 02/20/2026 01:16 (11), 02/20/2026 19:34 (1)
Complete: 🔍
Cache ID: 216::103

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