CVE-2026-118208: Microsoft Exchange Server improper access control spoofing

CVE-2026-118208 · Severity: high · CVSS 7.1 · Published 2026-11-10

Microsoft Exchange Server, an email and collaboration platform used by enterprises, contains an access control flaw that allows an authenticated attacker to spoof messages on the network. An attacker with valid credentials could impersonate other users or systems, potentially spreading malware, conducting phishing attacks, or disrupting communications.

Technologies: Microsoft Exchange Server. Vendors: Microsoft.

Quick answers

Is CVE-2026-118208 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-118208 being exploited in the wild.
How severe is CVE-2026-118208?
High severity, with a CVSS score of 7.1, published 10 November 2026.
Which products and versions are affected?
Microsoft Exchange Server.
Is there a fix for CVE-2026-118208?
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-2026-118208 attacked?
It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-118208?
Check whether you run Microsoft Exchange Server. 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

The vulnerability is an improper access control issue in Exchange Server that permits an authorized attacker to perform spoofing attacks over the network. The flaw allows authentication bypass or insufficient validation of sender identity, enabling message spoofing. A fix is available from Microsoft.

Affected products

  • Microsoft Exchange Server

Timeline

  • 2026-11-10: disclosed

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.