CVE-2026-58649: Microsoft .net

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

Origin validation error in .NET allows an unauthorized attacker to disclose information over a network.

Affected products

• Microsoft .net: version 11.0.0 only
• Microsoft .net SDK: from 8.0.100, before 8.0.130 (fixed in 8.0.130); from 8.0.200, before 8.0.424 (fixed in 8.0.424); from 9.0.100, before 9.0.120 (fixed in 9.0.120); from 9.0.200, before 9.0.317 (fixed in 9.0.317); from 10.0.100, before 10.0.111 (fixed in 10.0.111); from 10.0.200, before 10.0.400 (fixed in 10.0.400)
• Microsoft Visual Studio 2022: from 17.14.0, before 17.14.40 (fixed in 17.14.40)
• Microsoft Visual Studio 2026: from 18.9.0, before 18.9.3 (fixed in 18.9.3)

Published 2026-09-08. Last modified 2026-10-07.