CVE-2026-36799 in Tenda
Summary
by MITRE • 06/09/2026
Shenzhen Tenda Technology Co., Ltd Tenda G0 v15.11.0.5 was discovered to contain a buffer overflow in the portalAuth parameter of the formPortalAuth function. This vulnerability allows attackers to cause a Denial of Service (DoS) via a crafted HTTP request.
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Analysis
by VulDB Data Team • 06/09/2026
The vulnerability identified in Shenzhen Tenda Technology Co., Ltd Tenda G0 v15.11.0.5 represents a critical buffer overflow flaw within the device's web interface authentication mechanism. This issue specifically manifests in the formPortalAuth function where the portalAuth parameter fails to properly validate input length, creating an exploitable condition that can be leveraged by malicious actors to disrupt normal device operations. The buffer overflow occurs when an attacker submits a crafted HTTP request containing an excessively long portalAuth parameter value that exceeds the allocated buffer space, leading to memory corruption and subsequent system instability. This vulnerability falls under the CWE-121 category of Stack-based Buffer Overflow, which is a well-documented weakness in software systems where data written to a buffer exceeds the buffer's allocated size. The impact of this vulnerability extends beyond simple service disruption as it provides attackers with a mechanism to achieve Denial of Service conditions that can render the network device completely inaccessible to legitimate users.
The technical exploitation of this buffer overflow requires minimal sophistication and can be accomplished through standard web application attack methodologies. Attackers need only craft a specially formatted HTTP request that includes an overly long portalAuth parameter value, typically exceeding the buffer's allocated memory boundaries. When the device processes this malformed request, the overflow causes the application to crash or behave unpredictably, resulting in a denial of service condition that affects the device's ability to authenticate users and provide network services. The vulnerability demonstrates poor input validation practices and highlights the absence of proper bounds checking mechanisms within the device's web server implementation. This flaw is particularly concerning because it affects the authentication layer of the device, potentially allowing attackers to disrupt network access for authorized users while maintaining the device's operational state.
The operational impact of this vulnerability extends significantly beyond simple service disruption, as it can compromise the overall network infrastructure managed by the affected device. Network administrators may experience complete loss of device management capabilities, forcing them to manually intervene through physical access or alternative management channels. The DoS condition can persist until the device is manually rebooted or until the vulnerable software is patched and updated. This vulnerability affects the device's availability and reliability, potentially causing cascading failures in network services that depend on proper authentication mechanisms. The attack surface is particularly broad as the vulnerability is accessible through standard HTTP requests, making it trivial for attackers to exploit without requiring specialized tools or deep technical knowledge. The flaw also represents a potential entry point for more sophisticated attacks, as the device's compromised state may provide opportunities for privilege escalation or further exploitation of related vulnerabilities.
Mitigation strategies for this vulnerability should focus on immediate patching and configuration hardening measures. Device administrators should prioritize updating to the latest firmware version provided by Tenda, which should contain the necessary fixes for the buffer overflow condition. Until patches are applied, network administrators should consider implementing access controls that limit HTTP request access to trusted networks only, reducing the attack surface. Network segmentation and monitoring solutions should be deployed to detect and alert on suspicious HTTP request patterns that may indicate exploitation attempts. The vulnerability also highlights the importance of implementing proper input validation and bounds checking in all web applications, particularly those handling user-supplied data. Organizations should conduct regular security assessments of their network infrastructure to identify similar buffer overflow conditions in other devices and applications. The remediation process should include comprehensive testing of patched firmware to ensure that the vulnerability has been properly addressed without introducing new issues. Additionally, network administrators should establish incident response procedures specifically designed to handle device-level DoS conditions, ensuring rapid recovery and minimal disruption to network services.