CVE-2026-62897
High CVSS 7Published 2026-08-11 ยท last changed 2026-08-14
The fix
Microsoft fixes this in updatesKB5120698, KB5120703, KB5120747, KB5120711, KB5122106, KB5122104, KB5122105. 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 4.7.2 on Windows 10 Version 1809 for ARM64-based Systems | 2.0.50727.9070 & 3.0.30729.9068 & 4.7.4144.0 | KB5120698 | 2026-09-20 |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for ARM64-based Systems | 2.0.50727.9070 & 3.0.30729.9068 & 4.8.4805.0 | KB5120703 | 2026-09-20 |
| Microsoft .NET Framework 3.5 on Windows 11 Version 26H1 for ARM64-based Systems | 2.0.50727.9183 & 3.0.30729.9169 | KB5120747 | 2026-09-20 |
| Microsoft .NET Framework 3.5 on Windows 11 version 26H1 for x64-based Systems | 2.0.50727.9183 & 3.0.30729.9169 | KB5120747 | 2026-09-20 |
| Microsoft .NET Framework 4.8.1 on Windows 11 Version 26H1 for ARM64-based Systems | 4.8.9344.0 | KB5120711 | 2026-09-20 |
| Microsoft .NET Framework 4.8.1 on Windows 11 version 26H1 for x64-based Systems | 4.8.9344.0 | KB5120711 | 2026-09-20 |
| .NET 10.0 installed on Windows | 10.0.11 | KB5122106 | 2026-09-20 |
| .NET 8.0 installed on Windows | 8.0.30 | KB5122104 | 2026-09-20 |
| .NET 9.0 installed on Windows | 9.0.19 | KB5122105 | 2026-09-20 |
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
Integer overflow or wraparound in .NET Framework allows an unauthorized attacker to execute code locally.
Sources
CVSS vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H