CVE-2023-38936 in AC5
Summary
by MITRE • 08/07/2023
Tenda AC10 V1.0 V15.03.06.23, AC1206 V15.03.06.23, AC6 V2.0 V15.03.06.23, AC7 V1.0 V15.03.06.44, AC5 V1.0 V15.03.06.28, FH1203 V2.0.1.6, AC9 V3.0 V15.03.06.42_multi and FH1205 V2.0.0.7(775) were discovered to contain a stack overflow via the speed_dir parameter in the formSetSpeedWan function.
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Analysis
by VulDB Data Team • 01/21/2026
This vulnerability resides within multiple Tenda wireless router models including AC10 AC1206 AC6 AC7 AC5 FH1203 AC9 and FH1205 firmware versions. The issue manifests as a stack buffer overflow in the formSetSpeedWan function where the speed_dir parameter is processed without proper bounds checking. This allows remote attackers to craft malicious input that exceeds the allocated stack buffer space, potentially leading to arbitrary code execution or system crashes. The vulnerability represents a critical security flaw that could enable attackers to gain unauthorized control over affected devices.
The technical implementation of this vulnerability follows CWE-121 stack-based buffer overflow patterns where insufficient input validation permits data to overwrite adjacent stack memory locations. When the speed_dir parameter is processed through the formSetSpeedWan function, the firmware fails to validate the input length against the allocated buffer size, creating a condition where attacker-controlled data can overwrite return addresses and function pointers stored on the stack. This type of vulnerability is particularly dangerous as it can be exploited remotely without authentication, making it an ideal candidate for automated attacks targeting these specific router models.
From an operational perspective this vulnerability poses significant risks to network security and device integrity. Attackers can leverage this flaw to execute arbitrary code on affected routers, potentially gaining complete administrative control over the device. This could enable man-in-the-middle attacks, DNS hijacking, or the installation of persistent backdoors. The impact extends beyond individual devices as compromised routers can serve as entry points for broader network infiltration, particularly in enterprise environments where these devices often serve as primary network gateways. The vulnerability affects multiple firmware versions across different router models, indicating a widespread issue that requires immediate attention from network administrators.
Mitigation strategies should include immediate firmware updates from Tenda to address the buffer overflow condition in the formSetSpeedWan function. Network administrators should also implement network segmentation to limit the impact of potential exploitation and monitor for unusual traffic patterns that might indicate exploitation attempts. Additional defensive measures include disabling unnecessary services, implementing strict input validation at network boundaries, and conducting regular vulnerability assessments of network infrastructure. The ATT&CK framework categorizes this vulnerability under T1210 exploitation for execution and T1071 application layer protocols, emphasizing the need for both perimeter defense and internal network monitoring to detect potential exploitation activities.