SpectreMeltdownVarianten

SpectreMeltdownVarianten is a term used to describe the range of speculative execution vulnerabilities identified in modern CPUs, collectively known as Spectre and Meltdown. These flaws arise from the way processors perform speculative execution and use microarchitectural side channels, such as caches, which can leak information across protection boundaries.

The vulnerabilities are grouped into two broad families. Spectre exploits mispredicted speculative execution to access data that should be inaccessible, leaking it through observable timing and other side channels. Meltdown, by contrast, targets protection boundaries to allow transient execution that bypasses memory isolation, potentially exposing privileged data. Over time, researchers and vendors have documented multiple subvariants within these families, often labeled as Spectre Variant 1, Variant 2, and newer additions such as subsequent speculative-execution flaws. Related issues have also been given names like Foreshadow or L1 Terminal Fault (L1TF), and other speculative-store or cross-domain leakage flaws have been described in various advisories.

Impact and mitigations have evolved since the disclosures in 2017–2018. Mitigation approaches include processor microcode updates, operating system patches, and software techniques such as retpolines or kernel page-table isolation to reduce or eliminate leakage. Some mitigations incur performance costs due to changes in branch prediction, memory management, or caching behavior, and the landscape continues to evolve as new subvariants are discovered and addressed.

See also: Spectre, Meltdown, speculative execution, side-channel attacks.