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

> Attackers can access the Werkzeug debugger due to improper config parsing, leading to remote code execution or sensitive data disclosure.

- **Severity:** Critical 9.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Apr 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-92wx-pxch-p9px, GHSA-vg9h-jx4v-cwx2

## What is CVE-2026-40035?

CVE-2026-40035 is a critical vulnerability in obsidianforensics unfurl, published on 8 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-489 (Active Debug Code)

## Which versions are affected by CVE-2026-40035?

2 open source packages ship an affected version, including dfir-unfurl. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `dfir-unfurl` | PyPI | All versions to 20250810 | None |
| `dfir-unfurl` | PyPI | All versions to 20250810 | None |

Products: Ryandfir Unfurl.

## How do I fix CVE-2026-40035?

No fix has been published for CVE-2026-40035 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40035 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40035 exists.

## Other vulnerabilities in obsidianforensics unfurl

- [CVE-2026-40036](https://insights.sbomify.com/CVE-2026-40036/): Unfurl < 2026.04 - Denial of Service via Unbounded zlib Decompression (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40035 and fix it if it is affected.

What it is: CVE-2026-40035 is a critical vulnerability in obsidianforensics unfurl, published on 8 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40035 exists.

Affected packages and fixed versions:
- dfir-unfurl (PyPI): affected all versions up to 20250810; no fix listed
- dfir-unfurl (PyPI): affected all versions up to 20250810; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-40035/ (Markdown: https://insights.sbomify.com/CVE-2026-40035/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40035
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40035
- OSV: https://osv.dev/vulnerability/CVE-2026-40035

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40035/
Summaries are generated and may contain mistakes; the official description above is the record.