CVE-2022-26640 in TL-WR840N
Summary
by MITRE • 03/29/2022
TP-LINK TL-WR840N(ES)_V6.20 was discovered to contain a buffer overflow via the minAddress parameter.
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Analysis
by VulDB Data Team • 03/31/2022
The CVE-2022-26640 vulnerability affects TP-LINK TL-WR840N(ES)_V6.20 routers and represents a critical buffer overflow flaw in the device's web interface handling. This vulnerability resides within the router's management portal where the minAddress parameter is processed without proper bounds checking, creating an exploitable condition that could allow remote code execution or system compromise. The issue stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing, enabling attackers to craft malicious payloads that exceed the allocated buffer space. According to CWE-121, this vulnerability maps directly to stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations, potentially leading to arbitrary code execution.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with the ability to gain unauthorized access to the router's administrative functions. When an attacker submits a malformed minAddress parameter containing excessive data, the router's web server processes this input without adequate boundary verification, resulting in memory corruption that can be leveraged for privilege escalation or complete system takeover. The vulnerability demonstrates characteristics consistent with CWE-787, heap-based buffer overflow conditions, where improper input handling allows attackers to manipulate memory layout and potentially execute malicious code within the router's execution environment. This creates a significant risk for network security as compromised routers can serve as entry points for lateral movement within local networks, enabling attackers to establish persistent access or launch further attacks against connected devices.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, particularly under the T1059.007 technique for command and scripting interpreter, as successful exploitation could enable attackers to execute arbitrary commands on the affected device. The vulnerability also aligns with T1566.001 for spearphishing with a malicious attachment, as attackers might craft web-based payloads targeting this specific router model. Network defenders should implement immediate mitigations including firmware updates from TP-LINK, network segmentation to limit access to affected devices, and monitoring for anomalous web traffic patterns that might indicate exploitation attempts. The vulnerability underscores the importance of proper input validation and memory management practices in embedded systems, as highlighted by industry standards such as the OWASP Top 10 and NIST SP 800-160 guidelines for secure software development practices.
The technical exploitation of this vulnerability requires minimal prerequisites as attackers only need to access the router's web management interface, typically reachable through standard HTTP ports. The buffer overflow occurs during parameter parsing within the router's web server component, where the minAddress parameter is directly used in memory operations without proper length verification. This flaw represents a classic example of unsafe string handling in embedded network devices, where developers may have overlooked buffer size calculations or failed to implement proper bounds checking mechanisms. The vulnerability's severity classification as critical stems from its remote exploitability and potential for complete system compromise, making it a high-priority target for immediate remediation efforts across affected deployments. Organizations should prioritize patch management and network monitoring to detect potential exploitation attempts while implementing network access controls to limit exposure to this specific vulnerability.