How severe is CVE-2026-66803?

CVE-2026-66803 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-66803 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-66803?

CVE-2026-66803 affects Microsoft Azure Cosmos Db. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-66803?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-66803 published?

CVE-2026-66803 was published on 2026-07-30 and last updated on 2026-08-04.

CVE-2026-66803

CVE-2026-66803 is a critical-severity vulnerability in Microsoft Azure Cosmos Db with a CVSS 3.x base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-284.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
EPSS exploit prediction: 0% (40th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-284
Affected product: Microsoft Azure Cosmos Db
Published: 2026-07-30
Last modified: 2026-08-04

Description

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

Frequently asked questions

What is CVE-2026-66803?: Improper access control in Azure Cosmos DB allows an unauthorized attacker to execute code over a network.
How severe is CVE-2026-66803?: CVE-2026-66803 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-66803 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-66803?: CVE-2026-66803 affects Microsoft Azure Cosmos Db. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-66803?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-66803 published?: CVE-2026-66803 was published on 2026-07-30 and last updated on 2026-08-04.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66803

Affected products (1)

cpe:2.3:a:microsoft:azure_cosmos_db:-:*:*:*:*:*:*:*

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