CVE-2026-20563 in MT2716
Summary
by MITRE • 11/02/2026
In Modem, there is a possible out of bounds write due to an incorrect 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: MOLY01777997; Issue ID: MSV-8905.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability described involves a critical memory safety flaw within the modem firmware of mobile devices, specifically characterized as an out-of-bounds write resulting from an incorrect bounds check. This type of defect falls squarely under the Common Weakness Enumeration category CWE-787: Out-of-Bounds Write, which occurs when software writes data to a memory location beyond the intended buffer boundary. In the context of cellular modem architecture, such errors are particularly severe because they can corrupt adjacent memory structures or overwrite critical control flow data. The root cause is identified as an insufficient validation of input parameters before writing them into allocated buffers, allowing maliciously crafted data packets to exceed the designated limits and write into unauthorized memory regions.
The operational impact of this vulnerability centers on remote denial of service capabilities for connected user equipment. Because the flaw resides in the modem firmware, which operates independently from the main application processor's operating system security model, exploitation does not require elevated privileges or execution rights within the host OS. An attacker can leverage a rogue base station to transmit specially crafted signaling messages that trigger this out-of-bounds write condition when processed by the vulnerable UE. The immediate consequence is typically a crash of the modem subsystem, leading to a loss of cellular connectivity for the device user. In more complex scenarios involving memory corruption, such as heap or stack overflows, an attacker might potentially achieve arbitrary code execution, although the primary reported impact here is denial of service.
From a threat modeling perspective aligned with MITRE ATT&CK frameworks, this vulnerability facilitates techniques associated with Initial Access and Impact phases, specifically leveraging compromised network infrastructure to disrupt services. The attack vector requires the UE to connect to a rogue base station controlled by an adversary, which implies that physical proximity or sophisticated radio frequency attacks may be necessary depending on signal strength and range. However, no user interaction is required for exploitation once the connection is established, making it a passive threat that targets devices automatically attempting to register with available networks. This lack of user intervention significantly lowers the barrier for entry for attackers seeking to disrupt service availability in targeted areas or against specific high-value targets.
Mitigation strategies primarily involve applying the vendor-provided patch identified as MOLY01777997, which addresses issue MSV-8905 by correcting the bounds checking logic within the modem firmware. Organizations and individual users should ensure that device software is updated to include this fix promptly. Additionally, implementing network-level security controls such as detecting and blocking rogue base stations through advanced radio monitoring systems can reduce exposure. Users may also consider disabling automatic network selection features where possible, forcing manual connection choices to avoid inadvertently attaching to malicious infrastructure, although this trade-off impacts usability. Long-term resilience requires rigorous static analysis and fuzzing of modem code during development phases to identify similar memory safety violations before deployment.