CVE-2026-21553 in T8100
Summary
by MITRE • 08/03/2026
In modem, there is a possible improper input validation. This could lead to remote denial of service with no additional execution privileges needed
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Analysis
by VulDB Data Team • 08/03/2026
This vulnerability represents a critical weakness in modem firmware that stems from inadequate input validation mechanisms within the device's communication protocols. The flaw allows attackers to craft malicious input sequences that can trigger unexpected behavior in the modem's processing routines, ultimately resulting in a remote denial of service condition. Such vulnerabilities typically arise when the modem fails to properly sanitize or validate data received from external sources during normal operation, creating pathways for exploitation without requiring elevated privileges or malicious code execution. The absence of proper input validation creates a direct attack surface where malformed data can cause the modem to crash, restart unexpectedly, or enter an unusable state.
The technical implementation of this vulnerability manifests through the modem's failure to enforce strict boundaries on incoming data streams, particularly in areas such as command parsing, configuration updates, or network protocol handling. When the modem receives input that exceeds expected parameters or contains unexpected formatting patterns, the validation routines either completely bypassed or inadequately process these inputs, leading to memory corruption, resource exhaustion, or execution flow disruptions. This type of weakness aligns with common software vulnerabilities categorized under CWE-20, which specifically addresses improper input validation flaws in system components. The operational impact extends beyond simple service interruption as compromised modems can affect entire network connectivity for connected devices, potentially disrupting critical communications infrastructure.
From a threat landscape perspective, this vulnerability enables attackers to maintain persistent access to modem functionality without requiring privileged execution contexts or complex exploitation techniques. The remote nature of the attack means that adversaries can leverage publicly accessible communication channels or network interfaces to trigger the denial of service condition from external positions. This characteristic places the vulnerability in alignment with ATT&CK technique T1499.004, which covers network denial of service attacks targeting network infrastructure components. The lack of privilege requirements also suggests that this weakness could be exploited by automated scanning tools or opportunistic attackers who do not possess specialized knowledge of the target system's internal workings.
Organizations should implement comprehensive mitigation strategies that include firmware updates from vendors, network segmentation to limit exposure, and monitoring for anomalous input patterns that might indicate attempted exploitation. Regular vulnerability assessments of modem components are essential to identify similar validation weaknesses in other network infrastructure elements. Network administrators should also establish baseline operational parameters for modem behavior and implement automated alerting systems when service disruptions occur, enabling rapid response to potential exploitation attempts. The remediation approach must address both immediate patch deployment and long-term architectural improvements to prevent similar vulnerabilities from emerging in future implementations.