CVE-2015-4184: The anti-spam scanner on Cisco Email Security Appliance (ESA) devices 3.3.1-09, 7.5.1-gpl-022, and 8.5.6-07...

Security readout for executives and security teams

This Cisco Email Security Appliance issue could let a remote sender bypass intended anti-spam email restrictions using a malformed DNS SPF record. The sources do not show code execution or system takeover, but weakened mail filtering can increase business exposure to unwanted or risky email. Exposure is most likely where Cisco Email Security Appliance is still running one of the named builds and processing inbound email that evaluates sender SPF records. The source bundle does not identify broader products or versions. Treat this as a mail-security control weakness, not a confirmed breach indicator. Prioritize verification on active Cisco ESA gateways, especially those protecting executive, finance, or customer-facing mailboxes. Mitigation focus: Check Cisco advisory 39339 for affected-release guidance and any fixed versions or workarounds.; Inventory Cisco ESA appliances and compare installed builds against the named vulnerable versions.; Prioritize remediation for internet-facing mail gateways handling inbound external email..

Prepared

Jun 13, 2026, 22:39 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.