Affects ASP.NET Core, a widely used web framework; auth-bypass privilege escalation can impact many enterprise web apps and user data.
CVE-2026-47303
ASP.NET Core auth bypass via assumed-immutable data allows privilege escalation
Is CVE-2026-47303 being exploited?
Not confirmed. CVE-2026-47303 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 0.74% probability of exploitation in the next 30 days.
How severe is CVE-2026-47303?
CVE-2026-47303 is rated High with a CVSS score of 8.8. 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-2026-47303?
Yes. A fix has been recorded for CVE-2026-47303. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-47303 affect?
CVE-2026-47303 affects ASP.NET Core applications, ASP.NET Core framework, Web apps built on ASP.NET Core. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-47303?
Apply vendor patch; validate immutable inputs and enforce server-side authorization checks
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated attacker can bypass authorization by altering assumed-immutable data, elevating privileges to access/modify data and perform admin actions remotely.
Immediate action required
- affected>= 17.12.0 and < 17.12.22
- affected>= 17.14.0 and < 17.14.36
- affected>= 18.0 and < 18.7.4
- affected>= 10.0.0 and < 10.0.10
- affected>= 8.0.0 and < 8.0.29
- affected>= 9.0.0 and < 9.0.18
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.