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MsQuic has a Remote Elevation of Privilege Vulnerability

Critical severity GitHub Reviewed Published Apr 15, 2026 in microsoft/msquic • Updated Apr 16, 2026

Package

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

Affected versions

>= 2.5.0-ci.532574, < 2.5.7
< 2.4.18

Patched versions

2.5.7
2.4.18
nuget Microsoft.Native.Quic.MsQuic.Schannel (NuGet)
>= 2.5.0-ci.532574, < 2.5.7
< 2.4.18
2.5.7
2.4.18

Description

Summary

Improper input validation in Microsoft QUIC allows an unauthorized attacker to elevate privileges over a network.

Details

Improper Input Validation Integer Underflow (Wrap or Wraparound) when decoding ACK frame.

Patches

  • Fix underflow in ACK frame parsing - 1e6e999b

Impact

An attacker who successfully exploited this vulnerability could gain elevated privileges.

MSRC CVE Info

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-32179

References

@anrossi anrossi published to microsoft/msquic Apr 15, 2026
Published to the GitHub Advisory Database Apr 16, 2026
Reviewed Apr 16, 2026
Last updated Apr 16, 2026

Severity

Critical

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
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
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:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Weaknesses

Integer Underflow (Wrap or Wraparound)

The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. Learn more on MITRE.

CVE ID

CVE-2026-32179

GHSA ID

GHSA-gvvw-8j96-8g5r

Source code

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