Affects widely used ASP.NET Core; critical network-based privilege escalation could disrupt many apps across organizations.
CVE-2026-40372
Privilege escalation via improper cryptographic signature verification in ASP.NET Core.
Is CVE-2026-40372 being exploited?
Not confirmed. CVE-2026-40372 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 11% probability of exploitation in the next 30 days.
How severe is CVE-2026-40372?
CVE-2026-40372 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-40372?
Yes. A fix has been recorded for CVE-2026-40372. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-40372 affect?
CVE-2026-40372 affects ASP.NET Core. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-40372?
Monitor for patch; apply when released.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attacker can elevate privileges over the network due to signature verification flaw in ASP.NET Core.
Monitor only
- affected>= 10.0 and < 10.0.7
- affected>= 18.5.0 and < 18.5.2
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.