CVE-2026-108398
High CVSS 8.8Published 2026-10-13 ยท last changed 2026-10-13
The fix
Microsoft fixes this in updatesKB5126868, KB5127666, KB5127689, KB5127692, KB5127690, KB5127694, KB5127693, KB5127685, KB5127683, KB5127687, KB5127667, KB5127668, KB5127691, KB5127684, KB5127686, KB5127688. The fixed build differs per Windows version, so the row that matters is the one matching the machine you are looking at.
| Windows version | Fixed in build | Update | Released |
|---|---|---|---|
| Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows 10 version 1607 | 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0 | KB5126868 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016 | 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0 | KB5126868 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2019 | 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0 | KB5127666 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 version 1809 | 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0 | KB5127666 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 version 21H2 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 | KB5127689 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 version 22H2 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 | KB5127689 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 23H2 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 | KB5127692 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 24H2 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 | KB5127690 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 25H2 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 | KB5127690 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 26H2 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.10008.0 | KB5127694 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2022 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 | KB5127693 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2025 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 | KB5127690 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 version 1809 | 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0 | KB5127685 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 version 21H2 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.4811.0 | KB5127683 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 version 22H2 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.4811.0 | KB5127683 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2019 | 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0 | KB5127685 | 2026-10-13 |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022 | 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.4811.0 | KB5127687 | 2026-10-13 |
| Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 | 4.7.4150.0 | KB5127667 | 2026-10-13 |
| Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2 | 4.7.4150.0 | KB5127668 | 2026-10-13 |
| Microsoft .NET Framework 4.8.1 on Windows 11 version 26H1 | 4.8.9363.0 | KB5127691 | 2026-10-13 |
| Microsoft .NET Framework 4.8 on Windows 10 version 1607 | 4.8.4811.0 | KB5127684 | 2026-10-13 |
| Microsoft .NET Framework 4.8 on Windows Server 2012 | 4.8.4811.0 | KB5127686 | 2026-10-13 |
| Microsoft .NET Framework 4.8 on Windows Server 2012 R2 | 4.8.4811.0 | KB5127688 | 2026-10-13 |
| Microsoft .NET Framework 4.8 on Windows Server 2016 | 4.8.4811.0 | KB5127684 | 2026-10-13 |
Having the KB is not the same as knowing whether a machine has it. Windows updates supersede each other, so the update you installed often covers a fix that shipped in an earlier one. Paste your build into the patch checker and it walks that chain for you.
What it is
Untrusted search path in .NET Framework allows an authorized attacker to bypass a security feature locally.
Sources
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H