In the Linux kernel, the following vulnerability has been resolved: efivarfs: Rate limit statfs() handler Ravi reports that statfs() may be called… (CVE-2026-89604)
A vulnerability in the Linux kernel's efivarfs filesystem allowed unprivileged users to call statfs() on the efivarfs mount point, causing excessive calls to the QueryVariableInfo() runtime service. This service is costly on x86 systems due to the need for all CPUs to rendezvous for each call. The issue has been resolved by rate limiting these calls to twice per second and returning cached results for additional calls.
AI Analysis
Technical Summary
The Linux kernel vulnerability (CVE-2026-89604) involved unprivileged users invoking statfs() on efivarfs, which triggered a flood of calls to the QueryVariableInfo() runtime service. On x86 systems, each call requires a system management mode (SMM) entry that forces synchronization across all CPUs, making these calls disproportionately expensive. The fix implements a rate limit of two calls per second to QueryVariableInfo() and returns cached values for subsequent calls within that interval, mitigating the performance impact.
Potential Impact
Unprivileged users could cause a performance degradation on affected x86 systems by flooding the QueryVariableInfo() runtime service with calls via statfs() on efivarfs. This could lead to increased CPU synchronization overhead and potential system slowdowns. There is no indication of privilege escalation or direct security compromise beyond resource exhaustion.
Mitigation Recommendations
This vulnerability has been resolved by implementing rate limiting in the Linux kernel. Users should apply the official kernel update that includes this fix. No additional mitigation steps are necessary once the patch is applied.
In the Linux kernel, the following vulnerability has been resolved: efivarfs: Rate limit statfs() handler Ravi reports that statfs() may be called… (CVE-2026-89604)
Description
A vulnerability in the Linux kernel's efivarfs filesystem allowed unprivileged users to call statfs() on the efivarfs mount point, causing excessive calls to the QueryVariableInfo() runtime service. This service is costly on x86 systems due to the need for all CPUs to rendezvous for each call. The issue has been resolved by rate limiting these calls to twice per second and returning cached results for additional calls.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel vulnerability (CVE-2026-89604) involved unprivileged users invoking statfs() on efivarfs, which triggered a flood of calls to the QueryVariableInfo() runtime service. On x86 systems, each call requires a system management mode (SMM) entry that forces synchronization across all CPUs, making these calls disproportionately expensive. The fix implements a rate limit of two calls per second to QueryVariableInfo() and returns cached values for subsequent calls within that interval, mitigating the performance impact.
Potential Impact
Unprivileged users could cause a performance degradation on affected x86 systems by flooding the QueryVariableInfo() runtime service with calls via statfs() on efivarfs. This could lead to increased CPU synchronization overhead and potential system slowdowns. There is no indication of privilege escalation or direct security compromise beyond resource exhaustion.
Mitigation Recommendations
This vulnerability has been resolved by implementing rate limiting in the Linux kernel. Users should apply the official kernel update that includes this fix. No additional mitigation steps are necessary once the patch is applied.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-pmmg-3c8m-93q3
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-89604"]
Threat ID: 6aa4a00c55bf5e2cf5a86679
Added to database: 09/12/2026, 00:42:52 UTC
Last enriched: 09/12/2026, 01:02:59 UTC
Last updated: 09/12/2026, 01:02:59 UTC
Views: 2
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.