CVE-2024-35996: cpu: Re-enable CPU mitigations by default for !X86 architectures

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-20 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: cpu: Re-enable CPU mitigations by default for !X86 architectures Rename x86's to CPU_MITIGATIONS, define it in generic code, and force it on for all architectures exception x86. A recent commit to turn mitigations off by default if SPECULATION_MITIGATIONS=n kinda sorta missed that "cpu_mitigations" is completely generic, whereas SPECULATION_MITIGATIONS is x86-specific. Rename x86's SPECULATIVE_MITIGATIONS instead of keeping both and have it select CPU_MITIGATIONS, as having two configs for the same thing is unnecessary and confusing. This will also allow x86 to use the knob to manage mitigations that aren't strictly related to speculative execution. Use another Kconfig to communicate to common code that CPU_MITIGATIONS is already defined instead of having x86's menu depend on the common CPU_MITIGATIONS. This allows keeping a single point of contact for all of x86's mitigations, and it's not clear that other architectures *want* to allow disabling mitigations at compile-time.

Affected products

Debian Linux: 10.0
Linux kernel: from 5.15.156 before 5.15.158; from 6.1.87 before 6.1.90; from 6.6.28 before 6.6.30; from 6.8.7 before 6.8.9; 6.9-rc4, 6.9-rc5 — fixed in 5.15.158, 6.1.90, 6.6.30, 6.8.9

How to fix

Upgrade to a fixed version: Linux kernel 5.15.158, 6.1.90, 6.6.30, 6.8.9. Check the vendor advisory for mitigations.

References

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