Serious bug in fully patched Internet Explorer puts user credentials at risk
Microsoft engineers are working to patch universal XSS vulnerability. — A vulnerability in fully patched versions of Internet Explorer allows attackers to steal login credentials and inject malicious content into users' browsing sessions.
Context & Ripple Effects
This universal XSS bug lands in the middle of a long arc of Internet Explorer security failures documented across the coverage: Microsoft has already been forced into an emergency out-of-band patch for an IE vulnerability that hijacked Windows machines in August 2015, followed by a critical remote code execution flaw affecting all Windows versions since Vista in October's Patch Tuesday cycle. The pattern continued with another out-of-band security update in December 2018 for an RCE bug, and by January 2020 Microsoft was tracking an actively exploited IE bug on all Windows versions while users waited weeks for the next Patch Tuesday.
What makes this story matter is the target: fully patched browsers, meaning the standard enterprise defense of staying current provides no protection against credential theft and session injection until Microsoft ships a fix.
First-order effects
- Users of fully patched Internet Explorer are exposed right now: attackers can steal login credentials and inject malicious content into active browsing sessions while they wait for Microsoft's patch.
Second-order effects
- Enterprises standardized on IE face an impossible patching posture — the coverage shows this recurs, from the 2015 emergency fixes through the 2020 actively-exploited zero-day fixed only in the August Patch Tuesday batch — pushing IT departments toward third-party browser migration rather than riding out each disclosure.
Third-order effects
- A decade of repeated emergency patches and unpatched active exploitation points toward structural abandonment of legacy browser platforms: each incident erodes the case for keeping IE embedded in Windows workflows and accelerates consolidation around browsers with faster, independent patch cycles.
The trend: Internet Explorer's recurring unpatched vulnerabilities are converting Microsoft's bundled legacy browser from a default platform into a liability that pushes enterprises toward independently updated alternatives.