Azure App Service: Missing authentication leads to remote code execution
Summary
Microsoft Azure App Service is affected by a missing authentication flaw (CWE-306) in a critical function. An unauthenticated attacker on the network could execute code, which would have a total impact on confidentiality, integrity and availability. Microsoft states that it has fully mitigated the issue on its platform, so customers have no action to take.
Affected
- Microsoft Azure App Service (the MSRC record mentions Azure App Service for Linux; scope not clearly confirmed by Microsoft)
- Affected versions: Unknown. Microsoft published no build or version numbers.
Fixed in
- Fixed version: Not published. Microsoft has mitigated the issue on the service side; no customer update is required.
Workaround
- No customer-side workaround is required according to Microsoft.
- Generic hardening (not from Microsoft): restrict management and SCM endpoints with IP restrictions or private networking, and review access logs for unusual requests.
- Custom containers are the customer's responsibility. Keep your own base images and runtimes patched.
Exploitation
- Exploited in the wild: No, according to Microsoft at publication.
- Publicly disclosed: No.
- CISA KEV: Not listed.
- Public proof of concept: None found.
- Talos reports that one vulnerability disclosed in October 2026 was exploited, but does not identify this CVE. Verify against the MSRC exploitation flags.
Our recommendation
- No patch is required from customers; Microsoft has handled the fix.
- Check whether your organisation uses Azure App Service and whether its apps are internet-facing.
- Keep custom container images and application runtimes up to date.
- Monitor the MSRC advisory for changes to the affected versions or exploitation status.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide (vulnerability) msrc.microsoft.com
- Microsoft Security Update Guide (advisory) msrc.microsoft.com
- Talos: Microsoft Patch Tuesday October 2026 blog.talosintelligence.com
- Strix CVE summary www.strix.ai
- VulDB CVE-2026-77900 vuldb.com
- BDU FSTEC record BDU:2026-16747 vulners.com
- Microsoft App Service update on custom images azure.github.io
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 30 Oct 2026, 20:08.
Original description (NVD)
Missing authentication for critical function in Azure App Service allows an unauthorized attacker to execute code over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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