CVE-2026-40372 — Microsoft ASP.NET Core 10.0
As of 2026-04-22, CVE-2026-40372 is a CRITICAL-severity vulnerability in Microsoft ASP.NET Core 10.0, CVSS v3.1 9.1, EPSS 0.0% (11.6th percentile). Threadlinqs Intelligence links 2 tracked threat campaigns to CVE-2026-40372, most recently “ASP.NET Core Data Protection Authentication Cookie Forgery / Privilege Escalation (CVE-2026-40372)”.
Last updated: 2026-04-22
What is CVE-2026-40372?
Improper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to elevate privileges over a network.
The record classifies CVE-2026-40372 under weakness class CWE-347. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 145 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9.1 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS (FIRST)
- 0.0% probability of exploitation in the next 30 days, higher than 11.6% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-04-21, last modified 2026-04-22
Is CVE-2026-40372 being exploited?
It currently carries a trending score of 8 in the Threadlinqs vulnerability feed.
Affected products and versions
- Microsoft: ASP.NET Core 10.0, Visual Studio 2026 version 18.5
How to fix CVE-2026-40372
The record marks a vendor fix as available for CVE-2026-40372. Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40372. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-40372
2 tracked threats in the Threadlinqs corpus reference CVE-2026-40372, either in the campaign’s CVE list or as an indicator on the campaign record.
- ASP.NET Core Data Protection Authentication Cookie Forgery / Privilege Escalation (CVE-2026-40372) — CRITICAL · 2026-04-27
- CVE-2026-40372: ASP.NET Core Data Protection Authentication Cookie Forgery Enables Unauthenticated SYSTEM Privilege Escalation — CRITICAL · 2026-04-22
Sources
Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.
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