CVE-2026-23748 in Firmware SDK
Summary
by MITRE • 02/26/2026
Golioth Firmware SDK version 0.10.0 prior to 0.22.0, fixed in commit d7f55b38, contain an out-of-bounds read in LightDB State string parsing. When processing a string payload, a payload_size value less than 2 can cause a size_t underflow when computing the number of bytes to copy (nbytes). The subsequent memcpy() reads past the end of the network buffer, which can crash the device. The condition is reachable from on_payload, and golioth_payload_is_null() does not block payload_size==1. A malicious server or MITM can trigger a denial of service.
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Analysis
by VulDB Data Team • 02/26/2026
The vulnerability identified as CVE-2026-23748 affects the Golioth Firmware SDK version 0.10.0 through 0.21.0, representing a critical out-of-bounds read condition that can lead to device crash and denial of service. This flaw exists in the LightDB State string parsing functionality where the software fails to properly validate payload size parameters during network data processing. The vulnerability stems from a fundamental flaw in input validation logic where the system does not adequately check for minimum payload size requirements before proceeding with memory operations. The affected code path processes string payloads through the on_payload callback function, which serves as the primary interface for handling incoming network data from the Golioth cloud service. When a malicious actor or man-in-the-middle attacker sends a specially crafted payload with a size of less than two bytes, the system enters a dangerous state where arithmetic operations result in size_t underflow conditions.
The technical implementation of this vulnerability involves a specific mathematical operation that computes the number of bytes to copy (nbytes) during payload processing. When payload_size is less than 2, the arithmetic computation produces a negative value that, when interpreted as an unsigned integer, results in a massive positive value due to unsigned integer overflow behavior. This incorrect nbytes value is then passed to the memcpy() function, which attempts to read memory beyond the allocated network buffer boundaries. The underlying issue is that the golioth_payload_is_null() function, which should provide protection against malformed payloads, fails to block payloads with size exactly equal to one byte, creating a gap in the defensive logic. This gap allows the malformed payload to proceed through the normal processing flow until the critical memory operation occurs, resulting in undefined behavior and potential system crash.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise device availability and reliability in production environments. Devices running affected firmware versions become susceptible to remote exploitation by attackers who can manipulate network traffic to deliver malicious payloads that trigger the out-of-bounds read condition. The vulnerability is particularly concerning because it can be exploited through legitimate network communication channels without requiring physical access or elevated privileges. The crash condition affects the entire device runtime environment, potentially causing complete system failure and requiring manual intervention or automatic recovery mechanisms to restore normal operation. This vulnerability directly maps to CWE-129, which describes improper validation of array indices, and aligns with ATT&CK technique T1499.004 for network denial of service attacks. The exploitability of this vulnerability is high due to the minimal payload requirements needed to trigger the condition, making it an attractive target for attackers seeking to disrupt device operations.
The mitigation strategy for this vulnerability requires immediate deployment of firmware updates containing the fix committed as d7f55b38, which properly validates payload sizes before proceeding with memory operations. System administrators should prioritize patching affected devices in production environments, particularly those connected to critical infrastructure or IoT deployments where availability is paramount. Additional defensive measures include implementing network-level filtering to block malformed payloads and deploying intrusion detection systems that can identify suspicious communication patterns. The fix addresses the root cause by ensuring proper input validation in the payload processing pipeline, specifically modifying the golioth_payload_is_null() function to correctly handle edge cases and prevent underflow conditions. Organizations should also implement comprehensive testing procedures to validate firmware updates before deployment and establish monitoring protocols to detect potential exploitation attempts. The vulnerability demonstrates the importance of robust input validation in embedded systems and highlights the need for comprehensive security testing throughout the software development lifecycle to prevent similar issues in future releases.