CVE-2025-26412 is a vulnerability identified in the SIMCom SIM7600G modem, specifically in the firmware version LE20B03SIM7600M21-A. The issue stems from the presence of an undocumented AT command that allows an attacker to execute arbitrary system commands with root privileges on the modem itself. AT commands are standard instructions used to control modems, but this particular command is hidden and not documented by the vendor, SIMCom. Exploiting this vulnerability requires either physical access to the device or remote shell access to a device that communicates directly with the modem via AT commands. Once exploited, the attacker gains full control over the modem’s operating system, which can lead to severe consequences including manipulation of modem functionality, interception or modification of communications, or pivoting to other network components. The vulnerability is classified under CWE-912 (Hidden Functionality), indicating that the modem contains a backdoor-like feature that was not intended for public use. The CVSS v3.1 base score is 6.8, reflecting a medium severity level with high impact on confidentiality, integrity, and availability, but limited by the requirement of physical or remote shell access and the attack vector being physical. No known exploits are currently reported in the wild, and no patches have been published yet. This vulnerability highlights the risk of embedded device firmware containing undocumented commands that can be leveraged by attackers to gain privileged access.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on SIMCom SIM7600G modems in critical infrastructure, industrial IoT deployments, or communication gateways. The ability to execute commands as root on the modem can lead to interception or disruption of cellular communications, potentially affecting data confidentiality and integrity. Attackers could disrupt device availability or use the compromised modem as a foothold to attack connected systems. This is particularly concerning for sectors such as manufacturing, energy, transportation, and smart city deployments where cellular modems are used for remote monitoring and control. The requirement for physical or remote shell access somewhat limits the attack surface; however, in environments where devices are deployed in less secure or remote locations, the risk increases. Additionally, if an attacker gains remote shell access through other vulnerabilities, this modem flaw could be chained to escalate privileges and cause more severe damage. The lack of patches and public exploits means organizations should proactively assess their exposure and implement compensating controls to mitigate potential risks.

1. Inventory and Audit: Identify all devices using the SIMCom SIM7600G modem, particularly those running the affected firmware version LE20B03SIM7600M21-A. 2. Access Controls: Restrict physical access to devices containing the modem to trusted personnel only. 3. Network Segmentation: Isolate devices with SIM7600G modems from critical network segments to limit the impact of a potential compromise. 4. Secure Remote Access: Harden remote shell access mechanisms on devices interacting with the modem by enforcing strong authentication, using VPNs, and monitoring for unusual activity. 5. Firmware Updates: Engage with SIMCom or device vendors to obtain firmware updates or patches addressing this vulnerability. If unavailable, consider alternative hardware or firmware versions without this issue. 6. Monitoring and Detection: Implement monitoring for unusual AT command usage or unexpected modem behavior. Use intrusion detection systems to flag suspicious command executions. 7. Incident Response Planning: Prepare response plans for potential exploitation scenarios involving modem compromise. 8. Disable Unused Interfaces: Where possible, disable or restrict AT command interfaces to only authorized commands and users. These steps go beyond generic advice by focusing on controlling access to the modem interfaces, monitoring for exploitation attempts, and emphasizing the importance of firmware management and network architecture adjustments.