CVE-2026-20561 in MT2716
Summary
by MITRE • 11/02/2026
In Modem, there is a possible out of bounds write due to a missing bounds check. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01750090; Issue ID: MSV-8908.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability described constitutes a critical security flaw within the modem firmware of mobile devices, specifically characterized as an out-of-bounds write resulting from insufficient input validation. This type of memory corruption error occurs when the software writes data to a buffer beyond its allocated boundaries due to the absence of proper bounds checking mechanisms during processing operations. In the context of cellular communication protocols, such flaws are particularly dangerous because they reside in low-level components that handle raw network traffic before it is sanitized or processed by higher-layer application logic. The specific issue identified under patch ID MOLY01750090 and issue identifier MSV-8908 highlights a deficiency in how the modem handles certain data structures received from the base station, allowing an attacker to manipulate memory contents directly through malformed network packets.
From a technical perspective, this vulnerability aligns with Common Weakness Enumeration category CWE-787: Out-of-bounds Write. This classification indicates that the application accesses memory at an address outside of its intended buffer, which can overwrite adjacent memory locations containing critical control data such as return addresses or function pointers. Because modem firmware often operates in a privileged execution context to manage hardware resources and network stack operations, exploiting this flaw does not require additional privileges on the host operating system. The attacker leverages the inherent trust placed in cellular infrastructure by writing malicious payloads directly into the memory space of the modem processor via standard radio interface messages. This bypasses traditional application-level security controls since the exploitation occurs at the physical or link layer before data reaches the main CPU core running the device's OS.
The operational impact of this vulnerability is severe, primarily manifesting as a remote denial-of-service condition for the user equipment connected to the compromised network infrastructure. By triggering the out-of-bounds write, an attacker can corrupt critical state information within the modem firmware, leading to system instability, crashes, or permanent functional degradation requiring re-flashing of the device software. While some memory corruption vulnerabilities may allow for arbitrary code execution, in this specific instance, the primary consequence is service disruption. An adversary controlling a rogue base station can broadcast specially crafted signaling messages that exploit the missing bounds check, causing the modem to malfunction and effectively disconnecting the user from cellular services or rendering the device unusable until repaired. This represents a significant threat to availability, which is one of the three core pillars of information security alongside confidentiality and integrity.
This attack vector maps directly to MITRE ATT&CK techniques associated with network manipulation and resource exhaustion in mobile environments. Specifically, it relates to tactics involving interception or spoofing of cellular traffic by malicious base stations, often referred to as IMSI catchers or stingrays when used for surveillance, but here utilized purely for destructive purposes. The lack of user interaction required for exploitation means that any device within range of the rogue station is automatically vulnerable upon attempting to register with the network. This passive nature makes detection difficult without specialized monitoring tools capable of analyzing low-level radio protocol anomalies.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. The primary remediation involves applying the vendor-provided firmware update identified by MOLY01750090, which introduces rigorous bounds checking routines to validate all incoming data structures against their expected sizes before processing. Beyond software patches, device manufacturers should implement memory protection features such as Stack Canaries or Address Space Layout Randomization where applicable within the modem architecture. Network operators can also deploy detection systems that monitor for anomalous signaling patterns indicative of rogue base station activity, although this is challenging due to encryption and protocol complexity. Users are advised to keep their devices updated with the latest security patches and consider disabling automatic network selection if they operate in high-risk areas where unauthorized infrastructure might be present, forcing manual connection only to trusted networks.