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Vulnerability record · CVE-2026-40035 · published 8 April 2026

CVE-2026-40035: Ryandfir unfurl vulnerability

RRyandfir · Unfurl

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.

9.3 CVSS 4.0 Critical EPSS 0.72% · top 47.9% CWE-489 · CWE-489
9.3CVSS 4.0 base score
0.72%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 2 tagged exploit
24 Jul 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.7CVE-2026-40036Ryandfir unfurl allocation without limits vulnerabilityUnfurl before 2026.04 contains an unbounded zlib decompression vulnerability in parse_compressed.py that allows remote attackers to cause denial of s…EPSS 0.79%

Source: NIST National Vulnerability Database (record CVE-2026-40035), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.