---
id: CVE-2026-77900
title: >-
  Missing authentication for critical function in Azure App Service allows an
  unauthorized attacker to execute code over a network.
summary: >-
  Missing authentication for critical function in Azure App Service allows an
  unauthorized attacker to execute code over a network.
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-306
published: '2026-10-08'
updated: '2026-10-10'
sourceUpdated: '2026-10-10T04:18:14.030'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77900'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77900'
    label: secure@microsoft.com
tags:
  - nvd
  - cve.org
epss: 0.0072
epssPercentile: 0.53727
ingestedAt: '2026-10-09T00:19:50.974Z'
vendor: Microsoft
product: Azure App Service for Linux
affected:
  - azure_app_service_for_linux -
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-09T00:00:00+00:00'
---

## Overview

Missing authentication for critical function in Azure App Service allows an unauthorized attacker to execute code over a network.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.