# CVE-2026-6240: Authenticated Stack-based Buffer Overflow in ONVIF DeleteUsers Service on TP-Link Tapo C520WS

> An authenticated attacker can cause a denial of service on TP-Link Tapo C520WS cameras by triggering a stack-based buffer overflow in the ONVIF DeleteUsers service.

- **Severity:** Medium 6.8 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Jun 2026
- **Updated:** 8 Jun 2026
- **Also known as:** GHSA-qv33-m6vq-mqmr

## What is CVE-2026-6240?

CVE-2026-6240 is a medium-severity memory corruption vulnerability in TP-Link Systems Inc. Tapo C520WS v2, published on 5 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A stack-based buffer overflow vulnerability exists in Tapo C520WS v2 in the ONVIF DeleteUsers service, due to insufficient boundary checks when handling multiple user deletion parameters. An authenticated attacker can send a  crafted malicious request containing an excessive number of identifiers to overflow stack memory.

Successful exploitation may result in a service crash or deadlock, leading to DoS affecting device management and monitoring functionality.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-6240?


## How do I fix CVE-2026-6240?

No fix has been published for CVE-2026-6240 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-6240 being exploited?

There is no known exploitation of CVE-2026-6240 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6240 and fix it if it is affected.

What it is: CVE-2026-6240 is a medium-severity memory corruption vulnerability in TP-Link Systems Inc. Tapo C520WS v2, published on 5 Jun 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-2026-6240 in the wild and no public exploit code.

Affected product: TP-Link Systems Inc. Tapo C520WS v2. 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-2026-6240/ (Markdown: https://insights.sbomify.com/CVE-2026-6240/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6240
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6240
- OSV: https://osv.dev/vulnerability/CVE-2026-6240

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6240/
Summaries are generated and may contain mistakes; the official description above is the record.