# CVE-2026-6242: Authenticated Format String Vulnerability in ONVIF Subscribe Service on TP-Link Tapo C520WS

> An authenticated attacker can cause denial of service in the ONVIF Subscribe service of TP-Link Tapo cameras by injecting format strings.

- **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-m9ww-xwm5-pf57

## What is CVE-2026-6242?

CVE-2026-6242 is a medium-severity 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

An authenticated format string vulnerability exists in the ONVIF Subscribe service in Tapo C520WS v2 due to improper handling of externally supplied parameters within formatting functions. An attacker may inject crafted format strings into event subscription requests or notification generation path to disrupt normal service execution.

Successful exploitation may cause the event notification service to terminate unexpectedly, resulting in the loss of real-time alarm functionality and disruption of event notifications.

Weakness: CWE-134 (Use of Externally-Controlled Format String)

## Which versions are affected by CVE-2026-6242?


## How do I fix CVE-2026-6242?

No fix has been published for CVE-2026-6242 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-6242 being exploited?

There is no known exploitation of CVE-2026-6242 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6242 and fix it if it is affected.

What it is: CVE-2026-6242 is a medium-severity 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-2026-6242 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-2026-6242/ (Markdown: https://insights.sbomify.com/CVE-2026-6242/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6242
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6242
- OSV: https://osv.dev/vulnerability/CVE-2026-6242

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6242/
Summaries are generated and may contain mistakes; the official description above is the record.