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CVE-2026-40372

critical

Description

Improper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to elevate privileges over a network.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40372

https://www.bleepingcomputer.com/news/microsoft/microsoft-releases-emergency-security-updates-for-critical-aspnet-flaw/

https://thehackernews.com/2026/04/microsoft-patches-critical-aspnet-core.html

https://securityaffairs.com/191130/security/microsoft-out-of-band-updates-fixed-critical-asp-net-core-privilege-escalation-flaw.html

https://arstechnica.com/security/2026/04/microsoft-issues-emergency-update-for-macos-and-linux-asp-net-threat/

Details

Source: Mitre, NVD

Published: 2026-04-21

Updated: 2026-04-22

Risk Information

CVSS v2

Base Score: 9.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N

Severity: High

CVSS v3

Base Score: 9.1

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Severity: Critical

EPSS

EPSS: 0.00039

Vulnerability Watch

Tenable Research has classified this CVE under the following Vulnerability Watch classification, which includes active and historical (inactive) classifications. You can learn more about these classifications on our blog.

Vulnerability Being Monitored