# CVE-2020-35391: Information disclosure in n/a

> Remote attackers can obtain sensitive configuration data, including passwords, by requesting a specific configuration file from the router.

- **Severity:** Critical 9.6 (`CVSS:3.1/AC:L/AV:A/A:H/C:H/I:H/PR:N/S:C/UI:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Jan 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-mfx7-787g-3rp3

## What is CVE-2020-35391?

CVE-2020-35391 is a critical vulnerability in n/a, published on 1 Jan 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Tenda N300 F3 12.01.01.48 devices allow remote attackers to obtain sensitive information (possibly including an http_passwd line) via a direct request for cgi-bin/DownloadCfg/RouterCfm.cfg, a related issue to CVE-2017-14942. NOTE: the vulnerability report may suggest that either a ? character must be placed after the RouterCfm.cfg filename, or that the HTTP request headers must be unusual, but it is not known why these are relevant to the device's HTTP response behavior.

Weakness: CWE-425 (Direct Request)

## Which versions are affected by CVE-2020-35391?

It affects 1 product.


Products: Tenda F3 Firmware.

## How do I fix CVE-2020-35391?

No fix has been published for CVE-2020-35391 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-35391 being exploited?

There is no known exploitation of CVE-2020-35391 in the wild and no public exploit code.

Public exploit code:

- Tenda N300 Authentication Bypass via Malformed HTTP Request Header (github_poc): https://github.com/dumitory-dev/CVE-2020-35391-POC
- Python script to exploit CVE-2020-35391 on Tenda F3 V3/V4 routers, enabling unauthorized download of configuration, flash, and syslog files. (github_poc): https://github.com/4d000/Tenda-F3-V4
- Tenda f3 Malformed HTTP Request Header Processing Vulnerability. (github_poc): https://github.com/H454NSec/CVE-2020-35391
- Tenda N300 F3 12.01.01.48 - Malformed HTTP Request Header Processing (exploitdb)

## Other vulnerabilities in n/a

- [CVE-2026-27514](https://insights.sbomify.com/CVE-2026-27514/): Tenda F3 Plaintext Credential Exposure in Configuration Download (high 7.1)
- [CVE-2025-57569](https://insights.sbomify.com/CVE-2025-57569/): Memory corruption in n/a (medium 5.6)
- [CVE-2025-57570](https://insights.sbomify.com/CVE-2025-57570/): Memory corruption in n/a (medium 5.6)
- [CVE-2025-57571](https://insights.sbomify.com/CVE-2025-57571/): Memory corruption in n/a (medium 5.6)
- [CVE-2025-57572](https://insights.sbomify.com/CVE-2025-57572/): Memory corruption in n/a (medium 5.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-35391 and fix it if it is affected.

What it is: CVE-2020-35391 is a critical vulnerability in n/a, published on 1 Jan 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-35391 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2020-35391/ (Markdown: https://insights.sbomify.com/CVE-2020-35391/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-35391
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-35391
- OSV: https://osv.dev/vulnerability/CVE-2020-35391

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-35391/
Summaries are generated and may contain mistakes; the official description above is the record.