CVE-2018-3639 in Communications LSMS
Summary
by MITRE
Systems with microprocessors utilizing speculative execution and speculative execution of memory reads before the addresses of all prior memory writes are known may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis, aka Speculative Store Bypass (SSB), Variant 4.
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Analysis
by VulDB Data Team • 05/30/2026
The vulnerability identified as CVE-2018-3639 represents a critical side-channel flaw in modern microprocessors that leverage speculative execution mechanisms. This vulnerability specifically affects systems where the processor attempts to optimize performance by executing memory read operations before all preceding memory write operations have been definitively resolved. The issue stems from the processor's speculative execution engine which, in attempting to improve performance, may bypass certain memory ordering constraints that should normally prevent such premature execution patterns.
This vulnerability operates at the architectural level of processor design and falls under the broader category of speculative execution side-channel attacks. The flaw enables unauthorized information disclosure when an attacker with local user access can perform side-channel analysis to extract sensitive data from the processor's speculative execution behavior. The vulnerability is particularly concerning because it affects a fundamental aspect of processor operation that has been present in modern microprocessors for decades, making it widespread across numerous hardware platforms and system architectures.
The technical implementation of CVE-2018-3639 exploits the processor's tendency to speculatively execute memory reads before write addresses are fully resolved, creating a window where sensitive information can be accessed through timing analysis and cache behavior monitoring. This particular variant is classified as Variant 4 within the broader Speculative Store Bypass family of vulnerabilities and is categorized under CWE-1167, which addresses improper handling of speculative execution. The vulnerability demonstrates how performance optimization features can introduce security risks when not properly isolated from security-sensitive operations.
From an operational standpoint, this vulnerability creates a significant risk for systems where local user access can be gained through various attack vectors such as web application compromises, container escapes, or privilege escalation attempts. The impact extends beyond simple information disclosure to potentially enable more sophisticated attacks including credential theft, cryptographic key extraction, and other sensitive data breaches. Attackers can leverage this vulnerability through carefully crafted payloads that monitor cache states and timing variations to infer information from the processor's speculative execution behavior. The vulnerability affects a wide range of processors including those from intel and arm architectures, making it particularly dangerous for enterprise environments and cloud computing platforms where multiple users share hardware resources.
Mitigation strategies for CVE-2018-3639 typically involve both software and hardware approaches. Software mitigations include kernel-level patches and operating system updates that implement additional memory ordering constraints and prevent certain types of speculative execution patterns. Hardware mitigations involve processor microcode updates from manufacturers that modify the speculative execution behavior to prevent the vulnerable patterns. Organizations should implement comprehensive patch management programs and consider additional security controls such as memory protection techniques, privilege separation, and monitoring for anomalous system behavior. The vulnerability's classification under ATT&CK technique T1059.001 highlights its potential for abuse in command and control scenarios where attackers might use it to extract information from compromised systems.