CVE-2026-118154: Microsoft Exchange Server privilege elevation via untrusted security decision input

CVE-2026-118154 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Exchange Server, which handles corporate email and calendar services, contains a flaw where it relies on untrusted input to make security decisions. An authorized attacker can exploit this over the network to elevate their privileges beyond what they should have access to, potentially gaining administrative control or access to sensitive email data.

Technologies: Microsoft Exchange Server. Vendors: Microsoft.

Quick answers

Is CVE-2026-118154 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-118154 being exploited in the wild.
How severe is CVE-2026-118154?
High severity, with a CVSS score of 8.8, published 10 November 2026.
Which products and versions are affected?
Microsoft Exchange Server.
Is there a fix for CVE-2026-118154?
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-2026-118154 attacked?
It is attacked over the network.
Am I affected by CVE-2026-118154?
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 stems from reliance on untrusted inputs in a security decision within Microsoft Exchange Server, allowing privilege escalation. An authorized attacker can exploit this flaw over the network to elevate privileges. A fix is available from Microsoft.

Affected products

  • Microsoft Exchange Server

Timeline

  • 2026-11-10: disclosed

References

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