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Vulnerability record · CVE-2026-55009 · published 14 July 2026

CVE-2026-55009: Microsoft exchange server deserialization of untrusted data vulnerability

Microsoft · Exchange Server

Deserialization of untrusted data in Microsoft Exchange Server allows an authorized attacker to elevate privileges locally.

7.8 CVSS 3.1 High EPSS 2.5% · top 15.8% CWE-502 · Deserialization of untrusted data
7.8CVSS 3.1 base score
2.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
1References
24 Jul 2026Last modified by NVD

Description

Deserialization of untrusted data in Microsoft Exchange Server allows an authorized attacker to elevate privileges locally.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55009 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2024-21410Microsoft Exchange Server improper authentication privilege escalationCVE-2024-21410 is an improper authentication (CWE-287) elevation of privilege flaw in Microsoft Exchange Server. It is network-reachable with no priv…KEVEPSS 13%analysed9.1CVE-2021-34473Microsoft Exchange Server SSRF Enables Remote Code ExecutionCVE-2021-34473 is a critical server-side request forgery (SSRF) flaw in Microsoft Exchange Server that leads to remote code execution. It is part of …KEVEPSS 100%analysed9.1CVE-2021-26855Microsoft Exchange Server SSRF enabling remote code executionCVE-2021-26855 is a server-side request forgery (CWE-918) in Microsoft Exchange Server that is part of the ProxyLogon exploit chain and can lead to r…KEVEPSS 100%analysed9.0CVE-2021-34523Microsoft Exchange Server privilege escalation flawCVE-2021-34523 is a privilege escalation vulnerability in Microsoft Exchange Server. It is a component of the ProxyShell exploit chain, where it is u…KEVEPSS 100%analysed8.8CVE-2023-21529Microsoft Exchange Server deserialization flaw enables remote code executionCVE-2023-21529 is a deserialization of untrusted data vulnerability (CWE-502) in Microsoft Exchange Server that allows remote code execution. It carr…KEVEPSS 59%analysed8.8CVE-2022-41080Microsoft Exchange Server elevation of privilegeCVE-2022-41080 is an elevation of privilege vulnerability in Microsoft Exchange Server. A network-reachable attacker with low privileges can exploit …KEVEPSS 77%analysed8.8CVE-2022-41040Microsoft Exchange Server SSRF elevation of privilegeCVE-2022-41040 is a server-side request forgery (SSRF) flaw in Microsoft Exchange Server that allows an authenticated attacker to escalate privileges…KEVEPSS 100%analysed8.8CVE-2021-42321Microsoft Exchange Server remote code execution flawCVE-2021-42321 is a remote code execution vulnerability in Microsoft Exchange Server. It is remotely reachable over the network with low complexity, …KEVEPSS 92%analysed

Source: NIST National Vulnerability Database (record CVE-2026-55009), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.