CVE-2026-55009 json
Microsoft Exchange Server Elevation of Privilege Vulnerability
published 2026-07-14 3 mo ago modified 2026-11-01 7 d ago also EUVD-2026-44027
- cvss
- 7.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 2.5%
- EPSS 2.5% chance of exploitation in 30 days, percentile 84%
- public exploits
- 0
- none known
Summary
Deserialization of untrusted data in Microsoft Exchange Server allows an authorized attacker to elevate privileges locally.
Patch / fix
- Microsoft Microsoft Exchange Server 2016 Cumulative Update 23 15.01.2507.071
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 14 15.02.1544.043
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 15 15.02.1748.048
- Microsoft Microsoft Exchange Server Subscription Edition RTM 15.02.2562.045
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 3 mo ago
Exploit prediction
2.51% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C |
| CNA | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products
- Microsoft Microsoft Exchange Server 2016 Cumulative Update 23
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 14
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 15
- Microsoft Microsoft Exchange Server Subscription Edition RTM
Classification
- Weakness
-
- CWE-502 Deserialization of Untrusted Data
- Technology feeds
References
-
msrc.microsoft.com
/update-guide/vulnerability/CVE-2026-55009
vendor-advisory, patch
Sources
- CVE List CVE-2026-55009
- NVD CVE-2026-55009
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