CVE-2026-89604

Local denial of service via unthrottled statfs

Published Sep 11, 2026 · Updated Sep 11, 2026

Denial of service in Linux efivarfs allows local users to degrade x86 system responsiveness by repeatedly calling statfs(). The efivarfs_statfs() handler invokes the EFI QueryVariableInfo() runtime service for every request without rate limiting or cached results. An unprivileged user needs access to the efivarfs mount, and the greatest impact occurs on x86 systems whose firmware variable store uses SMM because each call rendezvouses all CPUs.

CVSS severityUnavailable
Unscored
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux efivarfs allows local users to degrade x86 system responsiveness by repeatedly calling statfs(). The efivarfs_statfs() handler invokes the EFI QueryVariableInfo() runtime service for every request without rate limiting or cached results. An unprivileged user needs access to the efivarfs mount, and the greatest impact occurs on x86 systems whose firmware variable store uses SMM because each call rendezvouses all CPUs.

The record

CVE
CVE-2026-89604
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=115409cbb6a296d73702a62c54c5b1b11cb88b3d
  2. Affected versionversion=6.1.178 <6.2
  3. Affected versionversion=6.5
  4. Affected versionversion=d86ff3333cb1d5f42d8898fb5fdb304e143c0237 <0dbc2e94b81df5a1264068b6ed3605c654b8afcb
  5. Affected versionversion=d86ff3333cb1d5f42d8898fb5fdb304e143c0237 <8953bdd1b9c0e748d5408d3d0b8e7aeee5c9cd41
  6. Affected versionversion=d86ff3333cb1d5f42d8898fb5fdb304e143c0237 <92895a14329cc9533e2a74a265214f690ba3851a
  7. Affected versionversion=d86ff3333cb1d5f42d8898fb5fdb304e143c0237 <b2326338dc683e8c1067c0cbf7a47986c4190902

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=115409cbb6a296d73702a62c54c5b1b11cb88b3d; version=6.1.178 <6.2; version=6.5; version=d86ff3333cb1d5f42d8898fb5fdb304e143c0237 <0dbc2e94b81df5a1264068b6ed3605c654b8afcb; version=d86ff3333cb1d5f42d8898fb5fdb304e143c0237 <8953bdd1b9c0e748d5408d3d0b8e7aeee5c9cd41; version=d86ff3333cb1d5f42d8898fb5fdb304e143c0237 <92895a14329cc9533e2a74a265214f690ba3851a; version=d86ff3333cb1d5f42d8898fb5fdb304e143c0237 <b2326338dc683e8c1067c0cbf7a47986c4190902

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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