# CVE-2026-66803 — Microsoft Azure Cosmos DB

> As of 2026-07-31, CVE-2026-66803 is a CRITICAL-severity vulnerability in Microsoft Azure Cosmos DB, CVSS v3.1 10, EPSS 0.4% (39.7th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-66803, most recently “CosmosEscape: Azure Cosmos DB Gremlin Sandbox Escape Exposed Platform-Wide Master Key (CVE-2026-66803)”.

**Last updated:** 2026-07-31

## What is CVE-2026-66803?

Improper access control in Azure Cosmos DB allows an unauthorized attacker to execute code over a network.

The record classifies CVE-2026-66803 under weakness class [CWE-284](https://intel.threadlinqs.com/cwe/CWE-284). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 67 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 10 — CRITICAL (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **EPSS (FIRST):** 0.4% probability of exploitation in the next 30 days, higher than 39.7% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 6.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-30, last modified 2026-07-31

## Is CVE-2026-66803 being exploited?

No public exploitation evidence for CVE-2026-66803 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-07-31. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

## Affected products and versions

- [Microsoft](https://intel.threadlinqs.com/vendors/microsoft): Azure Cosmos DB

## How to fix CVE-2026-66803

No vendor patch reference has been recorded for CVE-2026-66803 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-66803

1 tracked threat in the Threadlinqs corpus references CVE-2026-66803, either in the campaign’s CVE list or as an indicator on the campaign record.

- [CosmosEscape: Azure Cosmos DB Gremlin Sandbox Escape Exposed Platform-Wide Master Key (CVE-2026-66803)](https://intel.threadlinqs.com/threat/TL-2026-1779) — CRITICAL · 2026-07-30

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-08-01. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [msrc.microsoft.com — vendor advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66803)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-66803
Full detection coverage and IOCs for threats exploiting CVE-2026-66803 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp