CVE-2026-77900: CWE-306: Missing Authentication for Critical Function in Microsoft Azure App Service for Linux
Description
CVE-2026-77900 is a critical vulnerability in Microsoft Azure App Service for Linux where a missing authentication for a critical function allows unauthorized remote code execution. The flaw enables attackers to execute code over the network without any authentication. Microsoft has issued an official fix for this vulnerability. The vulnerability has a high CVSS score of 9.8, indicating severe impact on confidentiality, integrity, and availability. No known exploits are reported in the wild at this time.
CVSS v3.1
Score 9.8critical
Affected software
Microsoft
Azure App Service for Linux
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-77900) in Microsoft Azure App Service for Linux is due to missing authentication on a critical function, allowing an unauthenticated attacker to execute arbitrary code remotely. The CVSS 3.1 base score is 9.8, reflecting network attack vector, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Microsoft has published an official fix and manages remediation for this cloud-hosted service. No active exploitation has been observed.
Potential Impact
An attacker can remotely execute arbitrary code on the affected Azure App Service for Linux instance without authentication, potentially leading to full compromise of the service, including confidentiality, integrity, and availability impacts.
Mitigation Recommendations
Microsoft has released an official fix for this vulnerability and manages remediation for this cloud-hosted service. Users should ensure their Azure App Service for Linux instances are updated according to Microsoft's guidance at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77900. No additional mitigation steps are required beyond applying the official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2026-08-21T17:26:55.612Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Is Cloud Service
- true
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77900","vendor":"Microsoft"}]
Threat ID: 6ac81a602cdf04f6563e4d04
Added to database: 10/08/2026, 22:34:08 UTC
Last enriched: 10/08/2026, 22:48:32 UTC
Last updated: 10/08/2026, 22:49:04 UTC
Views: 17
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.