f2fs: avoid NULL checkpoint thread access in sysfs (CVE-2026-89835) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89835

f2fs: avoid NULL checkpoint thread access in sysfs

Answer in brief

CVE-2026-89835 records a Unknown severity vulnerability in f2fs: avoid NULL checkpoint thread access in sysfs. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 16, 2026Updated Sep 16, 2026Source checked Sep 16, 2026First seen by HOL Sep 16, 2026Material review Sep 16, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=e65920661708b7c0f3db45c9cd5d0095034ee37f <a6573f3ffc19542de9ebc1a2b1f930fd48ba538c \|\| >=e65920661708b7c0f3db45c9cd5d0095034ee37f <aefcec3bebdeed2bff444378122300763325ba23 \|\| >=e65920661708b7c0f3db45c9cd5d0095034ee37f <8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b \|\| >=e65920661708b7c0f3db45c9cd5d0095034ee37f <5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f	a6573f3ffc19542de9ebc1a2b1f930fd48ba538c, aefcec3bebdeed2bff444378122300763325ba23, 8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b, 5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f
Linux/Linuxgeneric	5.12	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to a6573f3ffc19542de9ebc1a2b1f930fd48ba538c if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 16, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: f2fs: avoid NULL checkpoint thread access in sysfs checkpoint_merge can be enabled even when no checkpoint merge thread is running. A read-only mount is one case: f2fs does not start f2fs_issue_ckpt there, but ckpt_thread_ioprio is still writable through sysfs. The ckpt_thread_ioprio store path updates the saved ioprio value and, when checkpoint_merge is enabled, calls set_task_ioprio() for the checkpoint thread. If cprc->f2fs_issue_ckpt is NULL, that dereferences a NULL task pointer. Protect ckpt_thread_ioprio sysfs writes with s_umount as well, so the checkpoint thread cannot disappear under the store path while updating its ioprio.

Quoted source text, attributed separately from HOL analysis.