# CVE-2026-5039: Predictable Default Cryptographic Key Used for DES Encryption in TP-Link TL-WL841N

> A predictable DES key in the TDDPv2 protocol allows network-adjacent attackers to read debug data, modify configurations, and cause device reboots.

- **Severity:** Medium 6.1 (`CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA: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:** 23 Apr 2026
- **Updated:** 28 Apr 2026
- **Also known as:** GHSA-f7mq-68q8-xqv6

## What is CVE-2026-5039?

CVE-2026-5039 is a medium-severity vulnerability in TP-Link Systems Inc. TL-WL841N v13, published on 23 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

TP-Link TL-WR841N v13 uses DES-CBC encryption in the TDDPv2 debug protocol with a cryptographic key derived from default web management credentials, making the key predictable if device is left in default configuration. A network-adjacent attacker can exploit this weakness to gain unauthorized access to the protocol, read debug data, modify certain device configuration values, and trigger device reboot, resulting in loss of integrity and a denial-of-service condition.

Weakness: CWE-1394 (Use of Default Cryptographic Key)

## Which versions are affected by CVE-2026-5039?

It affects 1 product.


Products: Tp-Link Tl-Wr841n Firmware.

## How do I fix CVE-2026-5039?

No fix has been published for CVE-2026-5039 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5039 being exploited?

There is no known exploitation of CVE-2026-5039 in the wild and no public exploit code.

## Other vulnerabilities in TP-Link Systems Inc. TL-WL841N v13

- [CVE-2022-25073](https://insights.sbomify.com/CVE-2022-25073/): Memory corruption in n/a (critical 9.8)
- [CVE-2018-12575](https://insights.sbomify.com/CVE-2018-12575/): Auth bypass in n/a (critical 9.8)
- [CVE-2022-46912](https://insights.sbomify.com/CVE-2022-46912/): File upload in n/a (high 8.8)
- [CVE-2020-35576](https://insights.sbomify.com/CVE-2020-35576/): Command injection in n/a (high 8.8)
- [CVE-2019-17147](https://insights.sbomify.com/CVE-2019-17147/): Memory corruption in TL-WR841N (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5039 and fix it if it is affected.

What it is: CVE-2026-5039 is a medium-severity vulnerability in TP-Link Systems Inc. TL-WL841N v13, published on 23 Apr 2026. 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-2026-5039 in the wild and no public exploit code.

Affected product: TP-Link Systems Inc. TL-WL841N v13. 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-2026-5039/ (Markdown: https://insights.sbomify.com/CVE-2026-5039/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5039
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5039
- OSV: https://osv.dev/vulnerability/CVE-2026-5039

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5039/
Summaries are generated and may contain mistakes; the official description above is the record.