CVE-2026-66085 in Modem
Summary
by MITRE • 10/12/2026
In modem, there is a possible information disclosure due to missing filtering of sensitive data in crash dumps. This could lead to local information disclosure with no additional execution privileges needed.
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Analysis
by VulDB Data Team • 10/12/2026
The vulnerability described involves a critical flaw within the firmware or software architecture of network modems, specifically concerning the handling and storage of system crash dumps. Crash dumps are diagnostic files generated by an operating system when it encounters a fatal error that prevents normal operation. These files contain a snapshot of the system's memory state at the time of the crash, which is essential for developers to debug issues and improve stability. However, in this specific instance, the modem fails to apply adequate filtering mechanisms before writing sensitive data into these dump files. This oversight results in the inclusion of high-value target information that should remain confidential, such as cryptographic keys, session tokens, user credentials, or internal network topology details. The presence of this unfiltered data transforms a routine diagnostic artifact into a significant security risk vector.
From a technical perspective, this flaw represents a classic case of improper output handling where sensitive context is persisted without sanitization. When the modem crashes and generates a dump file, it writes raw memory contents to non-volatile storage or makes them accessible via standard interfaces for debugging purposes. Because there are no checks in place to identify and mask sensitive variables before they are written to disk, any entity with access to these files can extract valuable intelligence. This is particularly dangerous because crash dumps are often stored in locations that may be readable by lower-privileged processes or even exposed through network services if the modem allows remote retrieval of logs for troubleshooting purposes. The lack of filtering means that the confidentiality integrity boundary between privileged system components and less trusted contexts is effectively bypassed simply by triggering a crash condition.
The operational impact of this vulnerability is severe, primarily due to its low barrier to exploitation. As noted in the description, no additional execution privileges are required to exploit this flaw if an attacker can induce a crash or access existing dump files. In many modem implementations, diagnostic logs and core dumps may be accessible via web interfaces, SNMP traps, or even through local file system access by unprivileged users within the device's operating system environment. An adversary who gains limited access to the modem could trigger conditions that cause crashes repeatedly, thereby generating multiple crash dumps containing sensitive data. Alternatively, if previous dump files are retained on the storage medium without secure deletion policies, an attacker could simply read these static files. The disclosure of cryptographic keys or session tokens can lead to complete compromise of encrypted communications, unauthorized access to backend services, or impersonation of legitimate users, undermining the fundamental security guarantees provided by encryption and authentication mechanisms.
This vulnerability aligns closely with CWE-532, which is defined as information exposure through log files. It also relates to CWE-798, involving the use of hardcoded credentials if sensitive keys are found in memory dumps, or more broadly CWE-200 regarding exposure of sensitive information to an unauthorized actor. In terms of offensive security frameworks like MITRE ATT&CK, this behavior facilitates reconnaissance and credential access techniques where attackers leverage system artifacts to gather intelligence without needing elevated privileges. The absence of proper data sanitization during the logging process is a common pitfall in embedded systems development, often stemming from rushed release cycles or insufficient threat modeling regarding diagnostic features.
To mitigate this risk, developers must implement strict filtering rules for all data written to crash dumps and log files. This involves identifying sensitive memory regions containing keys, passwords, tokens, and personally identifiable information, and ensuring these are masked or zeroed out before persistence. Additionally, access controls should be enforced on the storage locations of these diagnostic files, restricting read permissions to only highly privileged administrative accounts that require them for debugging. Implementing secure deletion policies is also crucial; crash dumps containing sensitive data should be automatically purged after a short retention period or once they have been securely transmitted to authorized support systems if remote diagnostics are enabled. Regular security audits and static code analysis focused on memory management and logging practices can help identify such oversights before deployment, ensuring that diagnostic features do not become vectors for information disclosure.