Unfurl - Werkzeug Debugger Exposure via String Config Parsing (CVE-2026-40035) | HOL Guard CVE

Critical · CVSS 9.3CVE-2026-40035GHSA-VG9H-JX4V-CWX2

Unfurl - Werkzeug Debugger Exposure via String Config Parsing

Answer in brief

CVE-2026-40035 records a Critical severity (CVSS 9.3) vulnerability in Unfurl - Werkzeug Debugger Exposure via String Config Parsing. The current sources do not mark it as known exploited. The current feed maps obsidianforensics/unfurl (generic), dfir-unfurl (pypi). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Apr 8, 2026Updated Sep 24, 2026Source checked Sep 24, 2026First seen by HOL Aug 8, 2026Material review Sep 24, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.3
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 9.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps obsidianforensics/unfurl (generic), dfir-unfurl (pypi). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
obsidianforensics/unfurlgeneric	>=0 <=2025.08	Not reported
dfir-unfurlpypi	>=0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for obsidianforensics/unfurl, dfir-unfurl.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Apr 8, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 8, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.