Quick answers
- Is CVE-2026-40379 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-40379 being exploited in the wild.
- How severe is CVE-2026-40379?
- Critical severity, with a CVSS score of 9.3, published 12 May 2026.
- Which products and versions are affected?
- Microsoft Entra ID All versions (Exclusively Hosted Service).
- Is there a fix for CVE-2026-40379?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-40379 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-40379?
- Check whether you run Microsoft Entra ID at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
Microsoft Entra ID is vulnerable to an information disclosure (CWE-200) that facilitates network-based spoofing. The vulnerability allows an unauthenticated attacker to access sensitive data, which can then be used to impersonate users or services. According to the CVSS vector, the attack requires user interaction (UI:R) and results in a scope change (S:C), impacting both confidentiality and integrity. As an exclusively hosted service, Microsoft typically manages the remediation on the backend, though administrators should monitor for suspicious authentication patterns.
Affected products
- Microsoft Entra ID All versions (Exclusively Hosted Service)
Timeline
- 2026-05-12: disclosed: Initial publication by Microsoft Corporation
- 2026-05-12: advisory: Microsoft Security Response Center advisory published