CVE-2026-0849 in Zephyr
Summary
by MITRE • 03/16/2026
Malformed ATAES132A responses with an oversized length field overflow a 52-byte stack buffer in the Zephyr crypto driver, allowing a compromised device or bus attacker to corrupt kernel memory and potentially hijack execution.
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Analysis
by VulDB Data Team • 03/20/2026
The vulnerability identified as CVE-2026-0849 represents a critical stack buffer overflow within the Zephyr real-time operating system crypto driver specifically targeting the ATAES132A cryptographic hardware module. This flaw exists in the handling of malformed responses from the cryptographic device, where an oversized length field in the communication protocol triggers memory corruption. The affected buffer size is precisely 52 bytes, which serves as the boundary for proper response parsing within the driver implementation. When an attacker crafts a response with an excessive length field, the driver fails to validate this parameter properly, leading to a classic stack-based buffer overflow condition.
The technical exploitation of this vulnerability occurs through the manipulation of communication protocols between the host system and the ATAES132A hardware module. The ATAES132A is a hardware security module designed for secure cryptographic operations, typically used in embedded systems and IoT devices where hardware-level encryption is required. The vulnerability stems from insufficient input validation within the Zephyr kernel's crypto driver implementation, which processes responses from the hardware module without proper bounds checking. This lack of validation allows an attacker to overwrite adjacent stack memory locations, potentially corrupting critical kernel data structures and execution flow control.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides a pathway for privilege escalation and potential system compromise. An attacker who can either gain physical access to the device or compromise the communication bus can craft malicious responses that trigger the buffer overflow. This scenario aligns with ATT&CK technique T1068, which covers the exploitation of legitimate credentials and system access for privilege escalation. The vulnerability could be exploited by an attacker who has already compromised the device or has access to the communication bus, potentially allowing them to execute arbitrary code within the kernel context, effectively gaining complete control over the system's operations.
The root cause of this vulnerability can be categorized under CWE-121, which describes stack-based buffer overflow conditions, and CWE-787, which addresses out-of-bounds write vulnerabilities. These classifications emphasize the fundamental issue of improper input validation and boundary checking within the cryptographic driver implementation. The vulnerability affects systems running Zephyr OS versions that include the ATAES132A driver, particularly those deployed in embedded environments where hardware security modules are utilized for cryptographic operations. The attack vector is primarily through physical access or bus manipulation, making it particularly concerning for IoT devices and embedded systems where such access might be possible.
Mitigation strategies for this vulnerability require immediate attention from system administrators and developers. The primary recommendation involves implementing proper input validation within the crypto driver to ensure that length fields in responses do not exceed expected boundaries. This includes adding bounds checking mechanisms that verify the length field against the maximum expected buffer size before processing the response data. Additionally, system updates should be applied immediately to patch the vulnerable driver implementation. The Zephyr project should implement defensive programming practices such as stack canaries and memory corruption detection mechanisms to prevent exploitation even if validation fails. Organizations should also consider implementing network segmentation and access controls to limit potential attack surfaces, particularly for devices that may be physically accessible to adversaries. The vulnerability highlights the importance of robust input validation in cryptographic implementations and serves as a reminder of the critical security considerations when integrating hardware security modules into embedded systems.