🎯 New Report #3590586: position: fixed !important bypasses CSS sanitizer's fixed-position mitigation, enabling full-viewport phishing overlays.
🔺Severity: Medium
👽 Reporter: nullcathedral
⭐️ Reputation: 150
🛠 State: resolved
💼 Team: Nextcloud
💵 Bounty: null
🕐 Submitted: 2026-03-07
⏰ Disclosed: 2026-04-20 12:04:03
📝 Summary: A vulnerability was discovered in the CSS sanitization process of the Roundcube webmail application. The sanitizer failed to properly handle the "position: fixed !important" CSS declaration, allowing an attacker to bypass the mitigation for fixed-position overlays. This could enable the creation of full-viewport phishing overlays.
📂 Report JSON File: 3590586
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