CVE-2026-118207: Microsoft Exchange Server Remote Code Execution Vulnerability
CVE-2026-118207 is a remote code execution vulnerability in Microsoft Exchange Server, rated Critical by Microsoft, with a CVSS 3.1 base score of 8.8 (High). An attacker can exploit it remotely over the network, with low privileges and without user interaction. Microsoft has not reported exploitation in the wild and rates exploitation as more likely. The EPSS model estimates a 1.15% probability of exploitation activity in the next 30 days, higher than 67% of all scored vulnerabilities. Microsoft released the fix on 10 November 2026 in the November 2026 Patch Tuesday, delivered through 1 security update (KB5133453). It affects 1 product in 1 product family (Server Software).
Key facts
- CVE ID
- CVE-2026-118207
- Severity
- High CVSS 8.8
- Microsoft severity
- Critical
- Impact
- Remote Code Execution
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- More Likely
- Weakness
- CWE-706
- EPSS
- 1.15% (percentile 67%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- Server Software
CVSS score and vector
Microsoft scores CVE-2026-118207 at 8.8 (temporal 7.7) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | High |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Description
Improper input validation in Microsoft Exchange Server allows an authorized attacker to execute code over a network.
Frequently asked questions (Microsoft)
How could an attacker exploit this vulnerability?
An authenticated attacker with low-level access to an affected server could send a specially crafted request to execute code on the server. User interaction is not required.
Affected products (1)
Server Software
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Microsoft Exchange Server Subscription Edition RTM | KB5133453 | Security Update | 15.02.2562.057 | Yes |
Security updates (1)
- KB5133453 (Security Update)
NIST NVD data
- NVD status
- Awaiting Analysis
- NVD CVSS
- 8.8 (HIGH)
- NVD weakness
- CWE-706
- Published to NVD
- NVD last modified
References
Acknowledgments
- Arjun Vasudeva with MSRC V&M
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |