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

• Severity: medium (CVSS 6.8 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-06 · updated 2026-07-23
• Weakness: CWE-134

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.

Affected products

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

How to fix

Upgrade to a fixed version: TP-Link Systems Inc. Tapo C520WS v2 1.2.6 Build 260528. Check the vendor advisory for mitigations.

References

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

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