CVE-2026-82929 in mH-DEVELOPER
Summary
by MITRE • 09/28/2026
mH-DEVELOPER smart home module uses the same hard-coded SSH host keys on every device, with no per-device key generation. An attacker who extracts these keys from the firmware can set up a rogue SSH server that clients will trust without warning, enabling man-in-the-middle attacks and credential interception. This issue was fixed in version 3.0.30
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Analysis
by VulDB Data Team • 09/28/2026
The mH-DEVELOPER smart home module exhibits a critical cryptographic implementation flaw characterized by the use of identical hard-coded SSH host keys across all manufactured units. In secure network architectures, each device should generate unique key pairs during initialization or manufacturing to ensure distinct identity verification. However, this vulnerability stems from a failure in key management practices where static private and public keys are embedded directly into the firmware image. This design decision eliminates the fundamental security property of uniqueness required for authenticating remote access services. Consequently, any attacker who gains read-only access to the device's storage media can extract these cryptographic materials without needing to exploit additional software bugs or perform complex reverse engineering beyond standard firmware extraction techniques.
The operational impact of this flaw is severe and directly facilitates man-in-the-middle attacks against users attempting to connect via SSH. Because all devices share the same host key fingerprint, an attacker who possesses the extracted keys can configure a rogue SSH server that presents the identical certificate as the legitimate mH-DEVELOPER module. When end-users or administrators attempt to establish a connection, their client software will recognize the presented key as trusted based on previous connections or default trust policies, thereby accepting the malicious host without issuing any security warnings. This allows the attacker to intercept all traffic between the client and the server, including authentication credentials such as usernames and passwords, session data, and potentially sensitive configuration commands sent during remote management sessions.
This vulnerability aligns with CWE-321, which describes the use of a hard-coded cryptographic key, indicating that the system relies on static secrets rather than dynamic or unique per-instance keys. From an offensive security perspective, this flaw enables techniques associated with MITM attacks and credential harvesting as documented in the ATT&CK framework under tactics related to Credential Access and Defense Evasion. The ability to impersonate a trusted service undermines the integrity of the administrative channel, allowing for complete compromise of device control and potential lateral movement within the home network if credentials are reused across other systems.
Mitigation strategies must focus on eliminating static key dependencies in favor of dynamic generation mechanisms. For existing devices that cannot be easily patched due to hardware constraints or lack of update infrastructure, administrators should disable SSH access entirely and rely on more secure alternatives such as HTTPS-based management interfaces with proper certificate validation if available. For future iterations and affected versions prior to the fix, it is imperative to enforce strict key rotation policies where possible through remote updates. The issue was addressed in version 3.0.30 of the mH-DEVELOPER firmware, which implements per-device key generation during production or first boot processes. Users are strongly advised to update their devices immediately upon release of this patch and verify that unique host keys are generated for each unit to restore trust boundaries within the SSH protocol stack.