CVE-2026-28627 in Android
Summary
by MITRE • 09/08/2026
In btm_sec_encrypt_change of btm_sec.cc, there is a possible downgrade attack due to a logic error in the code. This could lead to remote information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified within the bt_sec_encrypt_change function located in the btm_sec.cc source file represents a critical security flaw rooted in improper access control logic during Bluetooth security protocol negotiations. This specific implementation error allows an attacker to manipulate the encryption key size or algorithm selection process, effectively forcing the system to accept weaker cryptographic parameters than originally intended by the secure connection establishment procedure. By exploiting this logic gap, an adversary can initiate a downgrade attack that strips away essential layers of protection from the communication channel between devices. The core technical flaw lies in the failure of the function to strictly validate or enforce minimum security requirements before finalizing the encryption state change, thereby permitting the use of deprecated or weak cipher suites such as E0 or SNOOP which are susceptible to known cryptanalytic attacks.
From an operational perspective, this vulnerability facilitates remote information disclosure without requiring any prior authentication or execution privileges on the target device. The absence of a need for user interaction significantly lowers the barrier to entry for attackers, allowing them to exploit the flaw automatically through proximity-based wireless interactions. Once the encryption is downgraded, sensitive data transmitted over the Bluetooth link becomes vulnerable to interception and decryption by malicious actors within radio range. This includes personal identifiable information, authentication tokens, or proprietary business data that relies on the confidentiality guarantees provided by strong cryptographic standards. The impact extends beyond simple eavesdropping as it undermines the integrity of the entire secure channel, potentially leading further into man-in-the-middle scenarios where session hijacking is also possible if additional controls are not in place.
This vulnerability aligns with CWE-693 which describes Protection Mechanism Failure due to incorrect use of security features or logic errors that allow attackers to bypass intended safeguards. Furthermore it maps directly to the MITRE ATT&CK technique T1557 known as Adversary-in-the-Middle where an attacker intercepts and potentially alters communications between two parties who believe they are directly communicating with each other. The specific context of Bluetooth security protocols places this within the broader category of wireless protocol exploitation which has seen increased attention due to the pervasive nature of short-range connectivity in modern computing environments including smartphones laptops and IoT devices.
Mitigation strategies must focus on enforcing strict cryptographic policy enforcement at the point of negotiation rather than relying solely on default configurations or legacy compatibility modes that may inadvertently expose weaker algorithms. Developers should implement rigorous validation checks within bt_sec_encrypt_change to ensure that only approved strong encryption methods are permitted during state transitions. Additionally enabling forward secrecy and regularly updating Bluetooth stack implementations with vendor-provided security patches is essential for closing these gaps. System administrators can also mitigate risk by disabling unnecessary Bluetooth services when not in use and configuring devices to require explicit user confirmation before accepting new secure connections thereby adding a layer of human oversight that can prevent automated exploitation attempts from succeeding silently.