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Microsoft issues critical out-of-band patch for ASP.NET Core privilege escalation flaw

Evidence first: scan the strongest sources, then decide whether to go deeper.

Published 2026-04-22 09:29 UTCUpdated 2026-04-23 14:36 UTC
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cvevulnerabilitypatchprivilege_escalationmicrosoftincident_response
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Evidence trail (top sources)
top sources (4 domains)domains are deduped. counts indicate coverage, not truth.
4 top sources shown
ASP.NET Core 10.0: CVSS (Max): 9.1
AusCERT - Bulletins · News · portal.auscert.org.au · 2026-04-23 03:10 UTC
View all evidence
Overview

Microsoft released an urgent security update to fix a critical privilege escalation vulnerability (CVE-2026-40372) in ASP.NET Core's Data Protection Library.

Entities
MicrosoftASP.NET CoreMicrosoft DefenderIonut Arghire
Score total
1.3
Momentum 24h
4
Posts
4
Origins
4
Source types
1
Duplicate ratio
0%
Why now
  • The vulnerability was introduced in a recent Patch Tuesday update, affecting many developers and systems.
  • Attackers are actively exploiting these flaws, increasing urgency for patching.
  • Microsoft's out-of-band patch signals the critical nature and immediate risk posed by these vulnerabilities.
Why it matters
  • The ASP.NET Core vulnerability enables remote attackers to gain SYSTEM privileges, risking full system compromise.
  • Microsoft's quick patch release highlights the importance of timely updates to mitigate critical security flaws.
  • The exploitation of a zero-day in Microsoft Defender underscores ongoing threats to endpoint security.
LLM analysis
Topic mix: lowPromo risk: lowSource quality: high
Recurring claims
  • Microsoft released an out-of-band patch for a critical privilege escalation vulnerability in ASP.NET Core Data Protection Library (CVE-2026-40372).
  • The ASP.NET Core vulnerability allows attackers to bypass cryptographic validation and elevate privileges to SYSTEM level remotely.
  • A zero-day vulnerability in Microsoft Defender has been exploited to access the SAM database and gain system privileges.
How sources frame it
  • CSO Online: neutral
  • AusCERT: neutral
  • SecurityWeek: neutral
All evidence
All evidence
Recent Microsoft Defender Vulnerability Exploited as Zero-Day
SecurityWeek · securityweek.com · 2026-04-23 08:00 UTC
ASP.NET Core 10.0: CVSS (Max): 9.1
AusCERT - Bulletins · portal.auscert.org.au · 2026-04-23 03:10 UTC
Show filters & breakdown
Posts loaded: 0Publishers: 4Origin domains: 4Duplicates: -
Showing 4 / 0
Top publishers (this list)
  • SC Media (1)
  • SecurityWeek (1)
  • AusCERT - Bulletins (1)
  • CSO Online (1)
Top origin domains (this list)
  • scworld.com (1)
  • securityweek.com (1)
  • portal.auscert.org.au (1)
  • csoonline.com (1)