CVE-2026-89604
Low risk· EPSS 10%Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
In the Linux kernel, statfs() on the efivarfs mount point may be called by unprivileged users, which may result in a flood of calls to the QueryVariableInfo() runtime service. On x86 systems where the variable store is backed by SMM, each SMM entry requires a rendez-vous of all CPUs, making these calls disproportionately costly.
Risk Assessment
A flood of QueryVariableInfo() calls may lead to resource exhaustion and denial of service on x86 systems with efivarfs. The risk affects systems with unprivileged users having access to the efivarfs mount point.
Recommendation
Update the Linux kernel to a version containing the fix that rate limits QueryVariableInfo() calls to twice per second and returns the most recently obtained value for elided calls. Consider restricting access to the efivarfs mount point for unprivileged users.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: efivarfs: Rate limit statfs() handler Ravi reports that statfs() may be called by unprivileged users on the efivarfs mount point, which may result in a flood of calls to the QueryVariableInfo() runtime service. These calls are disproportionately costly on x86 systems where the variable store is backed by SMM, as each SMM entry requires a rendez-vous of all the CPUs. So rate limit the calls to QueryVariableInfo() at twice per second, and return the most recently obtained value for calls that are elided.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

