Vulnerability in Microsoft Exchange Server 2016 Cumulative Update 23

[ Description ]Official description

Improper verification of cryptographic signature in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• CERT-FR14 Oct 2026CERTFR-2026-AVI-1316

  Multiple vulnerabilities in Microsoft products Translated from French

  Multiple vulnerabilities have been discovered in Microsoft products. Some of them allow an attacker to cause remote arbitrary code execution, privilege escalation and remote denial of service.

  CVE-2026-88086CVE-2026-70007CVE-2026-70179+141 more CVEs
• BSI CERT-Bund13 Oct 2026WID-SEC-2026-3892

  Microsoft Windows and Windows Server: Multiple vulnerabilities Translated from German

  CVE-2026-69968CVE-2026-83785CVE-2026-72968+1124 more CVEs
• BSI CERT-Bund13 Oct 2026WID-SEC-2026-3920

  Microsoft Exchange: Multiple vulnerabilities Translated from German

  CVE-2026-87692CVE-2026-87695CVE-2026-70571+3 more CVEs
• NCSC-NL13 Oct 2026NCSC-2026-0419

  Vulnerabilities fixed in Microsoft Excange Server Translated from Dutch

  Probability/damage M/HCVE-2026-70279CVE-2026-70571CVE-2026-77910+4 more CVEs

[ References ]References

• msrc.microsoft.com/update-guide/vulnerability/CVE-2026-87696