CVE-2026-40035: Ryandfir Unfurl

Critical severity, CVSS 9.1. EPSS: 0.7% chance of exploitation in the next 30 days.

Unfurl through 2025.08 contains an improper input validation vulnerability in config parsing that enables Flask debug mode by default. The debug configuration value is read as a string and passed directly to app.run(), causing any non-empty string to evaluate truthy, allowing attackers to access the Werkzeug debugger and disclose sensitive information or achieve remote code execution.

Affected products

• Ryandfir Unfurl: up to and including 2025.08

Published 2026-04-08. Last modified 2026-10-08.