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Security Feature Bypass of Anti-amplification protection

High
guhetier published GHSA-2wmx-wr58-c2hg Oct 13, 2026

Package

nuget Microsoft.Native.Quic.MsQuic.OpenSSL (NuGet)

Affected versions

<2.6.3, <2.5.12

Patched versions

2.6.3, 2.5.12
nuget Microsoft.Native.Quic.MsQuic.Schannel (NuGet)
<2.6.3, <2.5.12
2.6.3, 2.5.12

Description

An all-zero PATH_RESPONSE frame sent before a PATH_CHALLENGE is issued by an MsQuic server would allow an attacker to bypass anti-amplification protections.

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-103577

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:H

CVE ID

CVE-2026-103577

Weaknesses

Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Learn more on MITRE.