CVE-2003-0121: Clearswift MAILsweeper 4.x allows remote attackers to bypass attachment detection via an attachment that do...

Security readout for executives and security teams

This is an old email-filter bypass in Clearswift MAILsweeper 4.x. An email attachment missing a MIME-Version header could avoid attachment detection, while some mail clients would still process it. Business risk is primarily legacy exposure: blocked file types or malicious attachments may have reached users despite gateway policy. Exposure is most likely in organizations still operating Clearswift MAILsweeper 4.x or reviewing historical mail-security controls from that era. The bundle’s affected-product metadata is incomplete, so confirmation should come from asset inventory and vendor documentation. Prioritize if legacy MAILsweeper 4.x remains in an active mail path. Otherwise, handle as a historical risk cleanup item and ensure current email security controls do not depend on a single MIME parser. Mitigation focus: Identify whether Clearswift MAILsweeper 4.x exists in production or archives.; Check Clearswift vendor guidance for fixed versions or configuration recommendations.; Retire or isolate unsupported legacy mail-filtering infrastructure..

Prepared

Jul 1, 2026, 05:06 UTC (UTC+00:00)

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