# CVE-2023-34140: Memory corruption in ATP series firmware

> An unauthenticated LAN attacker can cause denial of service in Zyxel network devices by sending a crafted request to the CAPWAP daemon.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 17 Jul 2023
- **Updated:** 21 Oct 2024
- **Also known as:** GHSA-65px-649g-rj37

## What is CVE-2023-34140?

CVE-2023-34140 is a medium-severity memory corruption vulnerability in Zyxel ATP series firmware, published on 17 Jul 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A buffer overflow vulnerability in the Zyxel ATP series firmware versions 4.32 through 5.36 Patch 2, USG FLEX series firmware versions 4.50 through 5.36 Patch 2,  USG FLEX 50(W) series firmware versions 4.16 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 4.16 through 5.36 Patch 2, VPN series firmware versions 4.30 through 5.36 Patch 2, NXC2500 firmware versions 6.10(AAIG.0) through 6.10(AAIG.3), and NXC5500 firmware versions 6.10(AAOS.0) through 6.10(AAOS.4), could allow an unauthenticated, LAN-based attacker to cause denial of service (DoS) conditions by sending a crafted request to the CAPWAP daemon.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2023-34140?

It affects 24 products.


Products: Zyxel Nxc2500 Firmware, Zyxel Nxc5500 Firmware, Zyxel Usg 20w-Vpn Firmware, Zyxel Usg 2200-Vpn Firmware, Zyxel Usg Flex 100 Firmware, Zyxel Usg Flex 100w Firmware, Zyxel Usg Flex 200 Firmware, Zyxel Usg Flex 500 Firmware, Zyxel Usg Flex 50 Firmware, Zyxel Usg Flex 50w Firmware, Zyxel Usg Flex 700 Firmware, Zyxel Zywall Atp100 Firmware, Zyxel Zywall Atp100w Firmware, Zyxel Zywall Atp200 Firmware, Zyxel Zywall Atp500 Firmware, Zyxel Zywall Atp700 Firmware, Zyxel Zywall Atp800 Firmware, Zyxel Zywall Vpn100 Firmware, Zyxel Zywall Vpn2s Firmware, Zyxel Zywall Vpn300 Firmware and 4 more.

## How do I fix CVE-2023-34140?

No fix has been published for CVE-2023-34140 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-34140 being exploited?

There is no known exploitation of CVE-2023-34140 in the wild and no public exploit code.

## Other vulnerabilities in Zyxel ATP series firmware

- [CVE-2023-34141](https://insights.sbomify.com/CVE-2023-34141/): Command injection in ATP series firmware (high 8.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-34140 and fix it if it is affected.

What it is: CVE-2023-34140 is a medium-severity memory corruption vulnerability in Zyxel ATP series firmware, published on 17 Jul 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-2023-34140 in the wild and no public exploit code.

Affected product: Zyxel ATP series firmware. 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-2023-34140/ (Markdown: https://insights.sbomify.com/CVE-2023-34140/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-34140
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-34140
- OSV: https://osv.dev/vulnerability/CVE-2023-34140

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-34140/
Summaries are generated and may contain mistakes; the official description above is the record.