How severe is CVE-2026-40372?

CVE-2026-40372 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-40372 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 11% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40372?

CVE-2026-40372 affects Microsoft Asp.net Core. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-40372?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-40372 have an EU (EUVD) identifier?

Yes. CVE-2026-40372 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-24249.

When was CVE-2026-40372 published?

CVE-2026-40372 was published on 2026-04-21 and last updated on 2026-06-27.

CVE-2026-40372

CVE-2026-40372 is a critical-severity vulnerability in Microsoft Asp.net Core with a CVSS 3.x base score of 9.1. Its EPSS exploit-prediction score of 11% places it in the 95th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-347.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 11% (95th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-24249
Weakness: CWE-347
Affected product: Microsoft Asp.net Core
Published: 2026-04-21
Last modified: 2026-06-27

Description

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

Frequently asked questions

What is CVE-2026-40372?: Improper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to elevate privileges over a network.
How severe is CVE-2026-40372?: CVE-2026-40372 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-40372 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 11% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40372?: CVE-2026-40372 affects Microsoft Asp.net Core. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40372?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-40372 have an EU (EUVD) identifier?: Yes. CVE-2026-40372 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-24249.
When was CVE-2026-40372 published?: CVE-2026-40372 was published on 2026-04-21 and last updated on 2026-06-27.

References

Affected products (1)

cpe:2.3:a:microsoft:asp.net_core:*:*:*:*:*:*:*:*

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