Double free in Microsoft Exchange Server - CVE-2026-55007
Published: September 8, 2026
Vulnerability identifier: #VU147473
CSH Severity: High
CVSS v4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-55007
CWE-ID: CWE-415
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to a double free in Microsoft Exchange Server when processing a specially crafted Visio attachment during content indexing. A remote attacker can send a specially crafted Visio attachment to an affected Exchange server to execute arbitrary code.
Successful exploitation requires the target system to be under sustained low-memory conditions.
Affected software
Microsoft Exchange Server
How to mitigate CVE-2026-55007
Install security update from vendor's website.
Microsoft Exchange Server - addressed in versions SE RTM Sep26SU 15.02.2562.049, 2019 CU14 Sep26SU 15.02.1544.046, 2019 CU15 Sep26SU 15.02.1748.051