CVE-2019-11091 in Intel
Summary
by MITRE
Microarchitectural Data Sampling Uncacheable Memory (MDSUM): Uncacheable memory on some microprocessors utilizing speculative execution may allow an authenticated user to potentially enable information disclosure via a side channel with local access. A list of impacted products can be found here: https://www.intel.com/content/dam/www/public/us/en/documents/corporate-information/SA00233-microcode-update-guidance_05132019.pdf
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Analysis
by VulDB Data Team • 05/29/2026
The vulnerability identified as CVE-2019-11091 represents a microarchitectural flaw categorized under the broader MDS (Microarchitectural Data Sampling) family of vulnerabilities that specifically targets uncacheable memory operations within modern processors utilizing speculative execution mechanisms. This vulnerability affects Intel processors and stems from the improper handling of data within the processor's microarchitecture, particularly concerning how uncacheable memory regions are managed during speculative execution phases. The flaw enables an authenticated user with local access to potentially exploit side-channel attack vectors that could lead to information disclosure through the manipulation of microarchitectural state.
The technical implementation of this vulnerability resides in the processor's handling of uncacheable memory accesses during speculative execution cycles. When the processor speculatively executes instructions that involve uncacheable memory operations, the data may remain in processor caches or microarchitectural structures even after the speculative execution has completed. This creates a persistent information leak that can be exploited through sophisticated side-channel techniques. The vulnerability specifically affects the processor's ability to properly invalidate or flush uncacheable memory data from microarchitectural buffers, allowing an attacker to potentially extract sensitive information from these residual data structures.
From an operational impact perspective, this vulnerability poses significant security risks to systems running affected Intel processors, particularly in environments where multiple users share the same physical hardware or when virtualization is employed. The authenticated local access requirement means that attackers must first gain user-level access to the system, but once achieved, they can potentially extract sensitive data such as cryptographic keys, passwords, or other confidential information stored in uncacheable memory regions. The vulnerability is particularly concerning in cloud computing environments and multi-tenant systems where isolation between different users or virtual machines may be compromised. This flaw represents a critical gap in processor security that affects not just individual systems but entire computing infrastructures that rely on speculative execution for performance optimization.
Mitigation strategies for CVE-2019-11091 primarily involve implementing microcode updates from Intel that address the specific microarchitectural issues within affected processors. System administrators should immediately apply the recommended microcode updates provided by Intel to patch the vulnerability at the processor level. Additionally, operating system-level mitigations and kernel parameters can be configured to further reduce the attack surface by disabling or limiting speculative execution features in certain contexts. The mitigation approach aligns with the broader ATT&CK framework's defense-in-depth principles, where multiple layers of protection are implemented to address vulnerabilities at different architectural levels. Organizations should also consider implementing monitoring solutions to detect potential exploitation attempts and establish incident response procedures to address any successful breaches. This vulnerability highlights the importance of continuous security assessment and the need for robust patch management processes to address microarchitectural flaws that may not be immediately apparent through traditional software vulnerability scanning methods. The issue is classified under CWE-200 (Information Exposure) and represents a significant concern in the context of modern processor security, where hardware-level vulnerabilities can undermine software-based security controls and require coordinated mitigation efforts across multiple system layers.