CVE-2006-6503: Mozilla Firefox 2.x before 2.0.0.1, 1.5.x before 1.5.0.9, Thunderbird before 1.5.0.9, and SeaMonkey before...

Security readout for executives and security teams

This is a legacy Mozilla browser and mail-client flaw from 2006. A malicious page or HTML content could bypass XSS protection by changing an image source to a javascript: URI, enabling script execution where protections should block it. Business risk is mainly in environments still running old Firefox, Thunderbird, or SeaMonkey builds. Exposure is likely limited to obsolete Mozilla installations or legacy Linux distributions that retained vulnerable packages. Modern supported browsers are not identified as affected in the supplied sources. Prioritize as a legacy hygiene issue unless discovery finds affected clients on active endpoints. The main business concern is old software handling untrusted web or HTML email content, not a newly disclosed widespread threat. Mitigation focus: Upgrade Firefox, Thunderbird, and SeaMonkey beyond the fixed versions named in the CVE.; Remove unsupported Mozilla clients from enterprise endpoints and golden images.; Check vendor advisories for distribution-specific package names and update paths..

Prepared

Jun 29, 2026, 08:45 UTC (UTC+00:00)

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