SB2026071628 - Multiple vulnerabilities in Microsoft Exchange Server
Published: July 16, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) Deserialization of Untrusted Data (CVE-ID: CVE-2026-55009)
CWE-ID: CWE-502 - Deserialization of Untrusted Data
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to escalate privileges on the target system.
The vulnerability exists due to insecure input validation when processing serialized data in Microsoft Exchange Server. A local user can pass specially crafted data to the application and gain elevated privileges on the system.
2) Cross-site scripting (CVE-ID: CVE-2026-55008)
CWE-ID: CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear
The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.
The vulnerability exists due to insufficient sanitization of user-supplied data in Microsoft Exchange Server. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website.
Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.
3) Insufficient Granularity of Access Control (CVE-ID: CVE-2026-55006)
CWE-ID: CWE-1220 - Insufficient Granularity of Access Control
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to insufficient granularity of access control in Microsoft Exchange Server, which leads to security restrictions bypass and privilege escalation.
4) Heap-based buffer overflow (CVE-ID: CVE-2026-55005)
CWE-ID: CWE-122 - Heap-based Buffer Overflow
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The vulnerability exists due to a boundary error in Microsoft Exchange Server. A remote user can pass specially crafted data to the application, trigger a heap-based buffer overflow and execute arbitrary code on the target system.
Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.
Remediation
Install update from vendor's website.