CVE-2026-93405
Mailspring: Stored XSS in attachment quick preview (unsanitized Markdown/DOCX/XLSX conversion)
Mailspring is a fast, cross-platform, open-source email client. Prior to 1.17.0, attachment quick preview converts Markdown, DOCX, and XLSX attachments with Snarkdown, Mammoth, and SheetJS and inserts the resulting HTML into the preview document through innerHTML without sanitization. A remote sender can craft a supported attachment whose converted HTML executes script when a recipient opens quick preview. The preview renderer has no direct Node or Electron access, but injected script can reach the IPC surface exposed to the quick-preview renderer. This issue alone provides script execution in the preview renderer; separate path-traversal and renderer-controlled file-write vulnerabilities are required for the documented persistent code-execution chain. This issue is fixed in version 1.17.0.
| CWE | CWE-79 |
| Vendor | foundry376 |
| Product | mailspring |
| Published | Sep 24, 2026 |
Get instant alerts for foundry376 mailspring
Be the first to know when new medium vulnerabilities affecting foundry376 mailspring are published — delivered to Slack, Telegram or Discord.
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N