CVE-2026-20462 in MT6739
Summary
by MITRE • 07/01/2026
In Telephony, there is a possible memory corruption due to a heap buffer overflow. This could lead to local escalation of privilege if a malicious actor has already obtained the System privilege. User interaction is not needed for exploitation. Patch ID: ALPS11006447; Issue ID: MSV-7871.
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Analysis
by VulDB Data Team • 07/01/2026
This vulnerability exists within telephony subsystem components where improper memory handling leads to heap buffer overflow conditions that can result in local privilege escalation. The flaw occurs when the system processes telephony-related data structures without adequate bounds checking, allowing attackers to write beyond allocated memory boundaries. Even though the initial compromise requires existing system-level privileges, the vulnerability creates a path for attackers to elevate their access further within the device's security model.
The heap buffer overflow represents a critical memory corruption issue that falls under CWE-121 Heap-based Buffer Overflow, where insufficient validation allows data to overwrite adjacent memory locations. This type of vulnerability is particularly dangerous because it can corrupt critical system structures including process control blocks, memory management tables, or privilege-related data structures. The exploitation does not require user interaction, meaning an attacker with system-level access can leverage this weakness autonomously without additional social engineering or manual intervention.
From an operational perspective, the impact extends beyond simple privilege escalation to potentially enable complete system compromise. Once elevated, an attacker could access sensitive telephony data including call logs, contact information, and potentially encryption keys used for secure communications. The vulnerability affects the fundamental memory management within telephony services, which typically run with high privileges to maintain system functionality while processing voice and data communications.
The security implications align with ATT&CK technique T1068, which covers Local Privilege Escalation through exploitation of system vulnerabilities. This attack vector allows adversaries to leverage existing system access to gain higher-level permissions that would otherwise be restricted. The patch ID ALPS11006447 and issue ID MSV-7871 indicate this is a vendor-specific fix addressing an internal security flaw in the telephony implementation.
Mitigation strategies should include immediate deployment of the vendor-provided patches to address the heap buffer overflow conditions. Organizations should also implement memory protection mechanisms such as stack canaries, address space layout randomization, and data execution prevention to reduce exploitability even if the underlying vulnerability persists. Regular security assessments of telephony subsystems and privileged processes are essential to identify similar memory corruption issues that could provide alternative escalation paths within the system architecture.
The vulnerability demonstrates how seemingly isolated components like telephony services can contain critical security flaws that serve as stepping stones for broader system compromise. The lack of user interaction requirements makes this particularly concerning from a threat modeling perspective, as it suggests an attacker with minimal access could automatically escalate privileges through automated exploitation. Network monitoring should also be enhanced to detect unusual patterns in telephony service behavior that might indicate exploitation attempts targeting this specific buffer overflow condition.