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Microsoft disclosed and patched CVE-2023-20588, an AMD processor information disclosure vulnerability known as AMD Speculative Leaks, after including mitigations in its December 2023 security updates. The flaw affects multiple AMD CPU families, including EPYC, Athlon, and Ryzen 3000-series processors, and stems from divide-by-zero behavior that can cause the processor to transiently return random or stale data during speculative execution.
The issue requires local access to exploit, but it was treated as a high-severity risk because sensitive data could be exposed from affected systems. Microsoft and CSIRT.SK said the vulnerability was identified by researchers from Microsoft Azure Research and Vrije Universiteit Amsterdam, and they urged organizations to apply Windows updates promptly. Guidance also advised developers to avoid using privileged data in divide-by-zero operations and to follow secure coding practices to reduce exposure.
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2 events from the most recent confirmed update back to the earliest known activity.
According to CSIRT.SK, Microsoft's December 2023 Patch Tuesday included fixes for CVE-2023-20588, a zero-day affecting AMD processors. Microsoft also published a Security Update Guide advisory for the issue.
CSIRT.SK states that CVE-2023-20588 was discovered by researchers from Microsoft Azure Research and Vrije Universiteit Amsterdam. The flaw is an information disclosure issue in AMD processors related to divide-by-zero behavior that can return transient or random data.
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Researchers disclosed the **Meltdown** and **Spectre** hardware flaws, showing that speculative execution in modern processors could let attackers read sensitive data across security boundaries on affected devices. Reuters reported that **Meltdown** primarily affected Intel processors by breaking memory isolation, while **Spectre** impacted Intel, AMD, and ARM chips by tricking applications into leaking secrets such as passwords and other protected data. CERT/CC later summarized the broader issue as cache side-channel attacks against CPU hardware using speculative execution, underscoring that the weakness was architectural rather than limited to a single product line. Major vendors and cloud providers moved to contain the fallout with software, firmware, and microcode mitigations, including Microsoft Azure protections for hosted customers and public advisories from manufacturers such as Huawei. Subsequent research showed the problem persisted beyond the initial disclosures: the **ZombieLoad** attacks demonstrated additional Intel data-leakage paths tied to speculative execution, and a later **TSX Asynchronous Abort (TAA)** variant affected some processors previously thought to be resistant. Intel issued microcode updates, but researchers and vendors warned that mitigations reduced rather than eliminated risk, that exploitation generally required local code execution, and that fully disabling the underlying CPU behavior would carry significant performance costs.
Jun 29, 2026
AMD has confirmed a high-severity vulnerability in the RDSEED instruction of its Zen 5 architecture CPUs, including Epyc 9005, Ryzen 9000, and Threadripper 9000 series. The flaw, tracked as CVE-2025-62626, allows the RDSEED function to return a value of 0 as a valid random number in approximately 10% of cases, potentially undermining the integrity of cryptographic keys and other security operations that rely on strong randomness. The issue was discovered by a Meta engineer and publicly disclosed via a Linux kernel mailing list, raising concerns about the predictability of cryptographic operations on affected systems. AMD has responded by releasing microcode patches for some affected processors, such as the Epyc 9005 series, and is working on additional fixes for other impacted models. As a temporary mitigation, users are advised to use the unaffected 64-bit RDSEED variant where possible or disable the RDSEED instruction via boot parameters. The vulnerability requires local privileges to exploit, meaning an attacker would already need significant access to the system. Linux kernel updates have also attempted to address the issue, though some users have reported compatibility problems with certain distributions following these changes.
Jul 12, 2026
Researchers disclosed the speculative-execution attacks **Meltdown** (`CVE-2017-5754`) and **Spectre** (`CVE-2017-5753`, `CVE-2017-5715`), showing that modern Intel, AMD, and ARM processors could leak sensitive data across privilege boundaries through cache-timing side channels. Google Project Zero demonstrated kernel and virtual-machine memory disclosure, while browser vendors including Mozilla confirmed that web content could abuse similar techniques, prompting Firefox to reduce timer precision and disable `SharedArrayBuffer` by default. Microsoft, Apple, Linux distributors, cloud providers, and hardware vendors issued operating-system, browser, and microcode mitigations, with Microsoft saying Azure had already been updated and Intel later announcing hardware changes for future chips. Early mitigation rollouts brought significant operational concerns, including uneven performance degradation and unstable firmware updates. Linux and macOS testing found that common desktop benchmarks often changed little, but syscall-heavy, storage, and IO-intensive workloads could slow noticeably, with some macOS microbenchmarks degrading by roughly **2x to 4x** and Windows Server or older systems expected to see larger impacts than newer Windows 10 devices. Intel’s early Spectre-related microcode updates were later linked to reboots and possible data corruption, leading Microsoft to publish an emergency update that disabled one mitigation path, while vendors such as Dell and NetApp tracked product exposure and remediation guidance as the industry continued responding to follow-on speculative-execution issues.
Jun 29, 2026