TONTOU and Spectre v2: Why “Mitigated” CPU Bugs Keep Coming Back on Linux

Post by **Gensys** » Sat Aug 15, 2026 1:45 pm

Speculative execution bugs did not end in 2018. They evolved. Research covered by BleepingComputer on a Spectre v2 bypass technique referred to as TONTOU is a reminder that CPU side channels remain a long game — especially on Linux systems where researchers demonstrated leakage risks including sensitive kernel memory contents in lab conditions.

Source: New TONTOU CPU attack bypasses Spectre v2 fixes — BleepingComputer

What is confirmed vs what is hype

Confirmed in public reporting of the research:

Spectre v2 style issues continue to produce new bypass techniques
Lab demos can leak sensitive data such as password hashes under specific conditions
Both Intel and AMD platforms have been part of testing narratives for this class of work

Not automatically true:

That every home desktop is “owned” tomorrow without local code execution / shared tenancy assumptions
That a single BIOS checkbox removes the entire class forever
That turning off all mitigations is free performance with no tradeoffs

Practical Linux admin posture

Track distro security advisories for microcode + kernel mitigation updates
Do not casually disable Spectre mitigations on multi-user or hosted boxes for benchmarks
Remember defense in depth: hashed passwords still need strong hashing + unique salts; leakage is bad either way
Shared hosting and CI runners have a different threat model than a single-user gaming PC

Discussion

For your personal machines, do you run full mitigations, selective ones, or “turn it off I want FPS” — and does that choice change on anything that faces a network?