CVE-2026-69439: .NET and Visual Studio Elevation of Privilege Vulnerability

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-08 · updated 2026-10-31
Weakness: CWE-122

Description

Heap-based buffer overflow in .NET and Visual Studio allows an unauthorized attacker to elevate privileges over a network.

Affected products

Microsoft .NET: from 8.0.0 before 8.0.31; from 9.0.0 before 9.0.20; from 10.0.0 before 10.0.12; 11.0.0-preview1, 11.0.0-preview2, 11.0.0-preview3, 11.0.0-preview4, 11.0.0-preview5, 11.0.0-preview6 (+1) — fixed in 8.0.31, 9.0.20, 10.0.12
Microsoft Visual Studio 2022 version 17.14: from 17.14.0 before 17.14.40 — fixed in 17.14.40
Microsoft Visual Studio 2026 version 18.9: from 18.9.0 before 18.9.3 — fixed in 18.9.3
Microsoft .NET 10.0 runtime: from 10.0.0 before 10.0.12 — fixed in 10.0.12
Microsoft .NET 11.0 runtime: from 11.0.0 before 11.0 RC1 — fixed in 11.0 RC1
Microsoft .NET 8.0 runtime: from 8.0.0 before 8.0.31 — fixed in 8.0.31
Microsoft .NET 9.0 runtime: from 9.0.0 before 9.0.20 — fixed in 9.0.20
Microsoft Visual Studio 2022 version 17.14: from 17.14.0 before 17.14.40 — fixed in 17.14.40
Microsoft Visual Studio 2026 version 18.9: from 18.9.0 before 18.9.3 — fixed in 18.9.3

How to fix

Upgrade to a fixed version: Microsoft .NET 8.0.31, 9.0.20, 10.0.12; Microsoft Visual Studio 2022 version 17.14 17.14.40; Microsoft Visual Studio 2026 version 18.9 18.9.3; Microsoft .NET 10.0 runtime 10.0.12; Microsoft .NET 11.0 runtime 11.0 RC1; Microsoft .NET 8.0 runtime 8.0.31; Microsoft .NET 9.0 runtime 9.0.20; Microsoft Visual Studio 2022 version 17.14 17.14.40; Microsoft Visual Studio 2026 version 18.9 18.9.3. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69439

Get alerted when CVE-2026-69439 or the next vulnerability affects your stack