CVE-2026-49934 in Android
Summary
by MITRE • 11/02/2026
In multiple functions of MmiUtils.java, there is a possible risk of USSD/MMI code execution due to improper input validation. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is needed for exploitation.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability identified in the Android framework component responsible for handling MMI and USSD codes represents a critical security flaw rooted in insufficient input sanitization within the MmiUtils.java class. Mobile Station International Dialing, commonly known as MMI codes, are special sequences used to interact with mobile network services such as call forwarding settings or line identification. Unstructured Service Center Data, or USSD, allows for real-time communication between a user's device and the mobile operator's service platform. The core technical flaw lies in the improper validation of input parameters passed through multiple functions within this utility class. Instead of strictly enforcing an allowlist of expected characters or formats, the implementation appears to accept arbitrary input strings without adequate verification against malicious payloads. This lack of rigorous boundary checking allows attackers to inject unintended commands that are subsequently processed by the underlying telephony stack as legitimate service requests.
From a technical perspective, this flaw facilitates local privilege escalation because it bypasses standard security controls designed to restrict access to sensitive system functions. Although exploitation requires user interaction, such as clicking on a malicious link or responding to a deceptive prompt containing the crafted MMI sequence, the resulting execution occurs with elevated privileges within the Android framework context. Once executed, these commands can modify critical network configurations, redirect calls to attacker-controlled numbers, or disable security features like call barring and forwarding restrictions. The absence of additional execution privileges for the initial exploit vector means that even a standard application running under normal user permissions can trigger this behavior if it successfully manipulates the input data fed into the vulnerable functions. This effectively allows an unprivileged process to alter system-level telephony settings, compromising the integrity of the device's communication infrastructure.
The operational impact of this vulnerability extends beyond simple configuration changes. An attacker leveraging this flaw could potentially intercept sensitive communications by redirecting voice calls or SMS messages intended for legitimate recipients. Furthermore, unauthorized modification of USSD-based services might lead to financial fraud if billing-related features are manipulated. In enterprise environments where mobile devices manage corporate data and network access, such a vulnerability poses significant risks to confidentiality and availability. The ability to escalate privileges locally without requiring root access makes this particularly dangerous in shared device scenarios or when users inadvertently engage with malicious content that triggers the vulnerable code paths.
Mitigation strategies must focus on strengthening input validation mechanisms within the affected Java classes. Developers should implement strict allowlist filtering for all MMI and USSD inputs, ensuring that only predefined, safe character sequences are processed by the telephony stack. Additionally, implementing context-aware checks to verify whether a command originates from a trusted system component rather than an arbitrary application can help prevent unauthorized execution. Updating to patched versions of the Android framework where these validation routines have been hardened is essential for immediate remediation. For end-users, maintaining up-to-date operating systems and exercising caution with unknown links or messages that might trigger USSD interactions remain vital defensive measures against exploitation attempts targeting this specific weakness in mobile device security architecture.