CVE-2026-6250: Tapo C110 v2 ONVIF Format String Vulnerability (CVSS 8.1)

Technical summary

CVE-2026-6250 is an authenticated format string vulnerability (CWE-134) in the ONVIF service component of the TP-Link Tapo C110 v2. The vulnerability stems from insufficient input validation on user-controlled data passed to format string functions. A remote attacker with valid ONVIF service credentials can craft malicious input that overwrites stack memory, including return addresses and other control flow data. By carefully constructing the format string payload, an attacker can redirect execution to existing code paths within the firmware that initiate a factory reset, resulting in immediate loss of configuration and stored credentials.

Business impact

Organizations deploying Tapo C110 v2 cameras for surveillance face service disruption and loss of critical monitoring capability if exploited. Factory reset wipes all device-level configurations, stored credentials, and access logs, necessitating manual reconfiguration of each affected camera. In multi-camera deployments, widespread exploitation could compromise network monitoring visibility. Additionally, if credentials are stored in a recoverable state pre-reset, attackers may capture them before the wipe, leading to lateral movement opportunities.

Affected systems

TP-Link Tapo C110 v2 cameras are the confirmed affected platform. The vulnerability exists in the ONVIF service, which is a standardized network camera interface protocol. Any deployment of Tapo C110 v2 hardware with ONVIF enabled is potentially vulnerable. The attack requires network access to the ONVIF service port and valid authentication credentials, limiting the attack surface to environments where ONVIF access is exposed or internally compromised.

Exploitability

Exploitation requires two conditions: (1) network reachability to the device's ONVIF service, and (2) valid authentication credentials. The lack of CVSS user interaction requirement (UI:N) indicates the attack occurs automatically once a request is sent, not requiring victim action. The attack complexity is rated low (AC:L), meaning no special conditions or race conditions are needed. While exploitation is technically straightforward for an authenticated attacker with ONVIF service knowledge, the authentication gate provides meaningful defense against external, unauthenticated threat actors.

Remediation

TP-Link should release a firmware update for the Tapo C110 v2 that sanitizes user input before it reaches format string functions, typically by removing format string specifiers or using safer string formatting APIs. Security teams should verify patch availability through TP-Link's support channels. Until patching is possible, network segmentation is critical: restrict ONVIF service access to trusted management networks, disable ONVIF if not actively used, and enforce strong, unique credentials for any ONVIF-enabled devices.

Patch guidance

Check TP-Link's official support page for Tapo C110 v2 firmware updates released after June 2026. Verify the release notes explicitly address CVE-2026-6250 or format string handling improvements. Apply patches in a controlled manner, testing on a non-production camera first to ensure no regression in functionality. Document the pre-patch configuration of affected cameras to streamline re-configuration if a pre-patch device is compromised. Consider enabling automatic firmware updates if the device supports this feature and your security policy permits it.

Detection guidance

Monitor ONVIF service logs on Tapo C110 v2 devices for unusual authentication patterns or failed requests. Look for suspicious input sequences containing format string specifiers ('%x', '%n', '%s') in ONVIF service requests, which may appear in network packet captures or device-level logging if available. Detect unauthorized factory resets through configuration management tools that track device settings; an unexpected reset to defaults is a strong indicator of exploitation. Network-based IDS/IPS signatures targeting format string exploitation in ONVIF traffic may help catch active exploitation attempts.

Why prioritize this

CVE-2026-6250 warrants immediate prioritization due to its HIGH CVSS score (8.1), high integrity and availability impact, and the practical consequences of factory reset in surveillance infrastructure. Although authentication is required, compromised or insider credentials are a realistic threat in many organizations. The direct availability impact—service disruption through unauthorized factory reset—makes this a critical operational security concern. Organizations with internet-facing ONVIF services or those with weak credential hygiene should treat this as a top-tier vulnerability.

Risk score, explained

The CVSS 3.1 score of 8.1 reflects: (1) Network-based attack vector (AV:N) with low complexity (AC:L) and low privilege requirements (PR:L), making exploitation feasible for authenticated users; (2) High impact on integrity (I:H) and availability (A:H), as the factory reset destroys configurations and credentials; (3) No impact on confidentiality (C:N), as the vulnerability does not expose sensitive data directly. The score appropriately reflects a serious but not critical flaw, as it does require prior authentication and does not grant arbitrary code execution.

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