CVE-2026-93405

MEDIUMCVSS 6.1/10

Last modified

CVE-2026-93405 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. 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.

Description

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.

Metrics

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
Foundry376Mailspring< 1.17.0

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-93405?
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.
How severe is CVE-2026-93405?
CVE-2026-93405 has a CVSS score of 6.1/10 (MEDIUM severity).
How do I fix CVE-2026-93405?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST