Microsoft Exchange Server: Remote Code Execution via code injection
Summary
A code injection flaw (CWE-94) in Microsoft Exchange Server Subscription Edition allows an authenticated attacker to execute code remotely over the network. The attacker needs a valid low-privilege account, but no user interaction is required. The CVSS base score is 8.8 (High), with possible full impact on confidentiality, integrity and availability.
Affected
- Microsoft Exchange Server Subscription Edition RTM: versions 15.02.0.0 before 15.02.2562.057
- Exchange Server 2016 and 2019: not listed in the CVE record; status unknown until MSRC confirms
Fixed in
- Exchange Server Subscription Edition: build 15.02.2562.057 or later (according to the CVE record)
- Security update (KB) number: unknown
Workaround
Unknown.
Exploitation
- No evidence of exploitation in the wild found at the time of writing
- CISA SSVC: exploitation none, automatable no, technical impact total
- Not listed in CISA KEV; no public proof of concept found
- NVD analysis is still pending
Our recommendation
- Check the MSRC advisory for the exact affected builds, the KB number and any mitigation
- Inventory all Exchange servers (Subscription Edition, 2019, 2016) and identify internet-facing OWA, ECP and EWS access
- Patch affected Subscription Edition servers as a priority, especially if they are exposed to the internet
- Review accounts with mailbox or admin rights and enforce MFA
- Monitor for KEV listing or public exploit code and re-check NVD
- If only Exchange Online is used, this CVE does not apply
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Microsoft Exchange Server
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation unlikely
- Product family
- Server software (Exchange, SharePoint …)
- Updates (KB)
- KB5133453
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Response Center: CVE-2026-118149 msrc.microsoft.com
- CVE Record: CVE-2026-118149 www.cve.org
- Strix: CVE-2026-118149 www.strix.ai
- Tenable: Microsoft November 2026 Patch Tuesday www.tenable.com
- Shadowserver: Vulnerable Exchange Server report www.shadowserver.org
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 10 Nov 2026, 22:27.
Original description (NVD)
Improper control of generation of code ('code injection') in Microsoft Exchange Server allows an authorized attacker to execute code over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
Affected? We can help.
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