CVE-2026-75118 in TL-MR100
Summary
by MITRE • 08/29/2026
A pre-authentication stack-based buffer overflow vulnerability exists in the http_gdpr_decrypt function of TL-MR100 V3.20 due to insufficient bounds checking of encrypted requests to the /cgi/login endpoint. An adjacent unauthenticated attacker with access to the router's web management interface can trigger memory corruption and potentially achieve arbitrary code execution.
Successful exploitation can overwrite saved control-flow data on the httpd process stack prior to authentication, resulting in a service crash or potential arbitrary code execution in the context of the affected process.
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Analysis
by VulDB Data Team • 08/29/2026
The vulnerability identified as CVE-2024-XXXXX represents a critical security flaw within the TP-Link TL-MR100 V3.20 router firmware, specifically located in the http_gdpr_decrypt function. This pre-authentication stack-based buffer overflow arises from insufficient bounds checking when processing encrypted requests directed at the /cgi/login endpoint. The core technical failure lies in the application's inability to validate the length of input data before copying it into a fixed-size buffer on the heap or stack, allowing an attacker to supply maliciously crafted payloads that exceed the allocated memory space. Because this function is invoked during the initial login process, which occurs prior to any authentication checks, the vulnerability can be exploited by an unauthenticated actor who has network access to the router's web management interface. This lack of prerequisite authentication significantly lowers the barrier for exploitation, making it accessible to remote attackers without valid credentials.
From a technical perspective, this flaw is classified under CWE-121: Stack-based Buffer Overflow, which describes situations where data written to a buffer exceeds its allocated size on the stack, leading to memory corruption. The attack vector involves sending specially crafted HTTP requests containing oversized encrypted payloads to the login endpoint. When the http_gdpr_decrypt function processes these requests, it fails to verify that the input length matches expected parameters before performing memory operations. This oversight allows an adjacent unauthenticated attacker to overwrite critical control-flow data on the stack of the httpd process. Such overwrites can include return addresses or other pointers used for program execution flow, thereby disrupting normal operation and potentially redirecting code execution to malicious shellcode injected by the attacker.
The operational impact of this vulnerability is severe, encompassing both service disruption and potential full system compromise. Successful exploitation results in memory corruption that typically manifests as a crash of the httpd process, leading to a denial-of-service condition where the web management interface becomes unavailable. However, beyond simple availability issues, the ability to overwrite control-flow data opens the door for arbitrary code execution with the privileges of the affected process. In many embedded router architectures, these processes run with elevated system rights or root-level access. Consequently, an attacker could gain complete control over the device, enabling them to intercept network traffic, install persistent malware, pivot into internal networks, or use the compromised device as part of a botnet for distributed denial-of-service attacks.
This vulnerability aligns with MITRE ATT&CK techniques related to initial access and privilege escalation via exploitation of remote services. Specifically, it reflects patterns seen in CWE-787: Out-of-bounds Write on Stack, which emphasizes the danger of unchecked writes to stack memory regions. The pre-authentication nature of this flaw places it among high-risk vulnerabilities that require immediate attention due to their ease of exploitation and significant impact potential. Attackers can leverage automated tools to scan for such weaknesses across large segments of internet-connected devices, making timely remediation essential for maintaining network integrity.
Mitigation strategies must focus on both immediate patching and long-term secure coding practices. The primary defense is the deployment of firmware updates provided by TP-Link that address this specific buffer overflow issue within the http_gdpr_decrypt function. Administrators should ensure their devices are updated to the latest stable release where bounds checking has been implemented correctly for all input data processed during authentication sequences. In environments where immediate patching is not feasible, network-level controls such as firewall rules restricting access to the web management interface from untrusted networks can reduce exposure. Additionally, implementing intrusion detection systems configured to detect anomalous HTTP request sizes or malformed payloads targeting login endpoints may provide an additional layer of defense against exploitation attempts until the underlying code defect is resolved through a software update.