Vulnerability in dfir-unfurl (CVE-2026-40035)
Summary
Vulnerability in dfir-unfurl (CVE-2026-40035). Confidential information can be exposed externally. Exploitable via debug.
Original description
The description as published by the source.
Summary
The Unfurl web app enables Flask debug mode even when configuration sets debug = False. The config value is read as a string and passed directly to app.run(debug=...), so any non-empty string evaluates truthy. This leaves the Werkzeug debugger active by default.
Details
unfurl/app.py:web_app()readsdebugviaconfig['UNFURL_APP'].get('debug'), which returns a string.UnfurlApp.__init__passes that string directly toapp.run(debug=unfurl_debug, ...).- If
unfurl.iniomitsdebug, the default argument is the string"True". - As a result, debug mode is effectively always on and cannot be reliably disabled via config.
PoC
- Create a local
unfurl.iniwithdebug = Falseunder[UNFURL_APP]. - Run the server using
unfurl_app(orpython -c 'from unfurl.app import web_app; web_app()'). - Observe server logs showing
Debug mode: on/Debugger is active!. - The included PoC script
security_poc/poc_debug_mode.py --spawnautomates this check.
PoC Script (inline)
#!/usr/bin/env python3
"""
Unfurl Debug Mode PoC (Corrected)
================================
This PoC demonstrates that Unfurl's Flask debug mode is effectively
**always enabled by default** due to string parsing of the `debug`
config value. Even `debug = False` in `unfurl.ini` evaluates truthy
when passed to `app.run(debug=...)`.
Two modes:
1) --spawn (default): launch a local Unfurl server with debug=False
in a temp config and inspect logs for "D…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-40035 has been found in dfir-unfurl.
Attackers can target a specific entry point like debug over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 9.1/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "dfir-unfurl CVE-2026-40035" on the vendor's site.
CVE-2026-40035 (dfir-unfurl) — CWE-489 / CVSS v3 9.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: debug / UnfurlApp.__init__ / unfurl.ini / unfurl_app
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-489) exists in dfir-unfurl. Attackers reach the vulnerable code path via debug without authentication.
Check the vendor advisory for the affected versions of dfir-unfurl. Attack surface: debug / UnfurlApp.__init__ / unfurl.ini / unfurl_app.
Severity: Critical (CVSS 9.1/10). Confidential information can be exposed externally.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'dfir-unfurl' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'dfir-unfurl' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
dfir-unfurlを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory disclosure@vulncheck.com
- exploit github.com
- package github.com
- web github.com