CVE-2026-89835Public exploitHinoki check available

Kernel crash via f2fs checkpoint thread dereference

Published Sep 16, 2026 · Updated Sep 16, 2026

NULL pointer dereference in Linux f2fs allows attackers with local sysfs write access to crash the kernel on a read-only mount. The ckpt_thread_ioprio store path calls set_task_ioprio() with a NULL f2fs_issue_ckpt task when checkpoint merging is enabled but no checkpoint thread exists. Exploitation requires permission to write the mounted filesystem's sysfs attribute; the demonstrated consequence is a kernel fault and service interruption.

CVSS severityUnavailable
Unscored
EPSS probabilityUnavailable
No score available in this record
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

NULL pointer dereference in Linux f2fs allows attackers with local sysfs write access to crash the kernel on a read-only mount. The ckpt_thread_ioprio store path calls set_task_ioprio() with a NULL f2fs_issue_ckpt task when checkpoint merging is enabled but no checkpoint thread exists. Exploitation requires permission to write the mounted filesystem's sysfs attribute; the demonstrated consequence is a kernel fault and service interruption.

The record

CVE
CVE-2026-89835
Published
Sep 16, 2026
Updated
Sep 16, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Sep 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=5.12
  2. Affected versionversion=e65920661708b7c0f3db45c9cd5d0095034ee37f <5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f
  3. Affected versionversion=e65920661708b7c0f3db45c9cd5d0095034ee37f <8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b
  4. Affected versionversion=e65920661708b7c0f3db45c9cd5d0095034ee37f <a6573f3ffc19542de9ebc1a2b1f930fd48ba538c
  5. Affected versionversion=e65920661708b7c0f3db45c9cd5d0095034ee37f <aefcec3bebdeed2bff444378122300763325ba23

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=e65920661708b7c0f3db45c9cd5d0095034ee37f <5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f; version=e65920661708b7c0f3db45c9cd5d0095034ee37f <8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b; version=e65920661708b7c0f3db45c9cd5d0095034ee37f <a6573f3ffc19542de9ebc1a2b1f930fd48ba538c; version=e65920661708b7c0f3db45c9cd5d0095034ee37f <aefcec3bebdeed2bff444378122300763325ba23

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

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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