Local privilege escalation via unsafe deserialization
Published Jul 14, 2026 · Updated Jul 14, 2026
Deserialization in Microsoft Exchange Server allows local users with low privileges to elevate privileges through untrusted serialized data. Microsoft identifies unsafe deserialization as the cause but has not disclosed the affected component, data path, or deserialization operation. Low-privileged local access is required; successful exploitation grants elevated control with confidentiality, integrity, and availability impact.
Summary
What happened
Deserialization in Microsoft Exchange Server allows local users with low privileges to elevate privileges through untrusted serialized data. Microsoft identifies unsafe deserialization as the cause but has not disclosed the affected component, data path, or deserialization operation. Low-privileged local access is required; successful exploitation grants elevated control with confidentiality, integrity, and availability impact.
The record
- CVE
- CVE-2026-55009
- Published
- Jul 14, 2026
- Updated
- Jul 14, 2026
- Vendor
- Microsoft
- Product
- Microsoft Exchange Server 2019 Cumulative Update 14
- Classifications
- CWE-502, CAPEC-586, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 14, 2026CVE publishedPublication date reported by the CVE source.
- Jul 14, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=15.02.0.0 <15.02.1544.043
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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