CVE-2026-70571

CVE-2026-70571 is a stack-based buffer overflow (CWE-121) in Microsoft Exchange Server. An unauthorized attacker can trigger it over the network without user interaction, though the attack complexity is rated high. Successful exploitation can lead to remote code execution with high impact on confidentiality, integrity, and availability (CVSS 3.1 base score 8.1). On-premises Exchange deployments are affected; specific version ranges are not given in the supplied data. It is not listed in CISA KEV, and no public proof-of-concept is known.

What to do: Apply Microsoft’s October 2026 security updates for Exchange Server as soon as they are available for your deployment. Until patched, limit network exposure of Exchange (especially from the internet), and review mail-server logs for unexpected remote code execution or crash activity. No public proof-of-concept or in-the-wild exploitation is indicated in the provided data.