CVE-2026-40035: Unfurl - Werkzeug Debugger Exposure via String Config Parsing

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-08 · updated 2026-10-08
Weakness: CWE-489

Description

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

obsidianforensics unfurl: through 2025.08

References

https://github.com/obsidianforensics/unfurl/security/advisories/GHSA-vg9h-jx4v-cwx2
https://www.vulncheck.com/advisories/dfir-unfurl-werkzeug-debugger-exposure-via-string-config-parsing
https://github.com/obsidianforensics/unfurl/security/advisories/GHSA-vg9h-jx4v-cwx2

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