# CVE-2022-43636: Auth bypass in TL-WR940N

> Network-adjacent attackers can bypass authentication on TP-Link TL-WR940N routers due to insufficient randomness in session sequence numbers.

- **Severity:** High 7.5 (`CVSS:3.0/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 29 Mar 2023
- **Updated:** 12 Feb 2025
- **Also known as:** GHSA-3fvg-68xh-vfxq

## What is CVE-2022-43636?

CVE-2022-43636 is a high-severity authentication bypass vulnerability in TP-Link TL-WR940N, published on 29 Mar 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

This vulnerability allows network-adjacent attackers to bypass authentication on affected installations of TP-Link TL-WR940N 6_211111 3.20.1(US) routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the httpd service, which listens on TCP port 80 by default. The issue results from the lack of sufficient randomness in the sequnce numbers used for session managment. An attacker can leverage this vulnerability to bypass authentication on the system. Was ZDI-CAN-18334.

Weakness: CWE-330 (Use of Insufficiently Random Values)

## Which versions are affected by CVE-2022-43636?

It affects 1 product.


Products: Tp-Link Tl-Wr940n Firmware.

## How do I fix CVE-2022-43636?

No fix has been published for CVE-2022-43636 yet. Limit exposure of the affected software until one is available.

## Is CVE-2022-43636 being exploited?

There is no known exploitation of CVE-2022-43636 in the wild and no public exploit code.

## Other vulnerabilities in TP-Link TL-WR940N

- [CVE-2023-36355](https://insights.sbomify.com/CVE-2023-36355/): Memory corruption in n/a (critical 9.9)
- [CVE-2022-24355](https://insights.sbomify.com/CVE-2022-24355/): Memory corruption in TL-WR940N (high 8.8)
- [CVE-2019-6989](https://insights.sbomify.com/CVE-2019-6989/): Memory corruption in n/a (high 8.8)
- [CVE-2026-11409](https://insights.sbomify.com/CVE-2026-11409/): OS Command Injection in IPv6 PPPoE Configuration in TP-Link TL-WR940N (high 8.5)
- [CVE-2026-11410](https://insights.sbomify.com/CVE-2026-11410/): OS Command Injection in BigPond Cable (BPA) Configuration in TP-Link TL-WR940N (high 8.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-43636 and fix it if it is affected.

What it is: CVE-2022-43636 is a high-severity authentication bypass vulnerability in TP-Link TL-WR940N, published on 29 Mar 2023. 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-2022-43636 in the wild and no public exploit code.

Affected product: TP-Link TL-WR940N. 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-2022-43636/ (Markdown: https://insights.sbomify.com/CVE-2022-43636/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-43636
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-43636
- OSV: https://osv.dev/vulnerability/CVE-2022-43636

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From sbomify Insights: https://insights.sbomify.com/CVE-2022-43636/
Summaries are generated and may contain mistakes; the official description above is the record.