CVE-2026-35088 in IPx
Summary
by MITRE • 10/15/2026
Slican telephone exchanges use symmetric encryption for TCP/IP communication. Secret key is hardcoded in multiple binary files. An attacker who has access to these files can decrypt the communication.
This issue was fixed in IPx series version 6.62.0100.
The issue STILL EXISTS in End-Of-Life telephone exchanges: - CCT-1668 (CCT1CPU) - MAC-6400 - CXS-0424 These products were discontinued in 2011 and 2012 and and will not receive updates. These products require a hardware update in order to receive a software update. The vendor recommends that users of these devices contact the their service department directly to determine the options for upgrading.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described involves a critical failure in cryptographic key management within Slican telephone exchanges, specifically affecting older models such as the CCT-1668, MAC-6400, and CXS-0424 systems that utilize symmetric encryption for TCP/IP communications. The core technical flaw lies in the implementation of the encryption mechanism where the secret key is hardcoded directly into multiple binary files rather than being generated dynamically or stored securely in a hardware-backed keystore. This approach violates fundamental principles of secure software development, as it removes any possibility of rotating keys or changing credentials without recompiling and redeploying the entire firmware image. Consequently, if an attacker gains access to these binary files through physical theft, network interception leading to reverse engineering, or other means of extracting embedded code, they can easily extract the static secret key. Once obtained, this key allows the attacker to decrypt all past and future communications protected by that specific instance of encryption, effectively nullifying the confidentiality guarantees provided by the protocol.
From a technical perspective, this vulnerability aligns with CWE-798: Use of Hard-coded Credentials, which is widely recognized as one of the most severe weaknesses in software security due to its permanence and ease of exploitation. The use of symmetric encryption itself is not inherently flawed, but the method of key storage renders it insecure because symmetric algorithms require both parties to share the same secret key, making distribution and protection paramount. In this scenario, hardcoding the key ensures that every device running the affected firmware version shares identical cryptographic material across potentially thousands of units globally. This lack of unique per-device or per-session keys means a single compromise affects all systems using that binary build, creating a massive blast radius for any successful attack. The vulnerability also reflects CWE-321: Use of Hard-coded Cryptographic Key, emphasizing the specific danger in cryptographic implementations where static keys are embedded directly into source code or compiled binaries instead of being managed through secure key management services.
The operational impact of this flaw is severe, particularly given that these telephone exchanges handle sensitive voice and signaling data often classified as critical infrastructure components within telecommunications networks. An adversary with network access who can perform a man-in-the-middle attack could intercept encrypted TCP/IP traffic between exchange nodes or between the exchange and connected endpoints. By applying the extracted hardcoded key to decrypt this stream, the attacker gains full visibility into call details, potentially including caller identification, duration, timing, and any unencrypted payload data transmitted over these connections. Beyond confidentiality loss, if integrity checks are also compromised by knowledge of the encryption scheme, an attacker might attempt message injection or modification attacks, disrupting service availability or manipulating signaling protocols to redirect calls or cause denial-of-service conditions. This level of access undermines trust in the telecommunications infrastructure and poses significant risks to privacy and operational continuity for organizations relying on these legacy systems.
The situation is further complicated by the end-of-life status of the affected products, specifically the CCT-1668, MAC-6400, and CXS-0424 models which were discontinued in 2011 and 2012. Because no software updates are planned to remediate this issue through a simple patch, mitigation requires more drastic measures. The vendor explicitly states that these products require a hardware update to receive any form of security improvement, implying that the architecture itself may be limited by its original design constraints regarding secure key storage capabilities such as Trusted Platform Modules or similar hardware security modules which were likely not present in older generations. For organizations still operating these systems, immediate isolation from untrusted networks is recommended to limit exposure. Network segmentation should be enforced so that any remaining communication occurs only over highly controlled and monitored internal segments with strict access controls. Additionally, since the vendor recommends contacting their service department directly for upgrade options, stakeholders must engage in proactive lifecycle management discussions to plan for hardware replacement or specialized retrofitting solutions before total obsolescence leads to unmitigated risk exposure.
In terms of threat modeling, this vulnerability maps to ATT&CK technique T1530: Data from Information Repositories if the attacker retrieves binaries containing keys, and potentially T1048: Exfiltration Over Alternative Protocol if encrypted channels are abused for data theft after decryption capabilities are established. The persistence of such flaws in legacy industrial control systems and telecommunications equipment highlights a broader industry challenge where security updates cease long before hardware is physically retired. Organizations must conduct thorough asset inventories to identify these specific Slican models and assess their network exposure. Until physical upgrades or replacements can be implemented, compensating controls such as deep packet inspection for anomalies, strict firewall rules limiting TCP/IP ports used by the exchanges, and regular audits of binary integrity using checksums against known good versions from secure archives are essential defensive measures to detect potential tampering attempts that might precede key extraction.