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NVD / CVE Program· CNA Linux

CVE-2026-89835: f2fs: avoid NULL checkpoint thread access in sysfs

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.21% (FIRST EPSS).
  • Fixed version: Linux Linux 22760e3e9cecbddc475edc91600787abf407a302, 54196bcfde998fb37009f50e0ef16498f651f0f9, 5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 22760e3e9cecbddc475edc91600787abf407a302, 54196bcfde998fb37009f50e0ef16498f651f0f9, 5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

—No exploit Fix available
Published
Sep 16, 2026
Updated
Oct 30, 2026
EPSS
0.2% · 11th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when exploit code appears or is weaponized
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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.12affected
    • e65920661708b7c0f3db45c9cd5d0095034ee37f and later · before 54196bcfde998fb37009f50e0ef16498f651f0f9affected · git
    • e65920661708b7c0f3db45c9cd5d0095034ee37f and later · before 22760e3e9cecbddc475edc91600787abf407a302affected · git
    • e65920661708b7c0f3db45c9cd5d0095034ee37f and later · before a6573f3ffc19542de9ebc1a2b1f930fd48ba538caffected · git
    • e65920661708b7c0f3db45c9cd5d0095034ee37f and later · before aefcec3bebdeed2bff444378122300763325ba23affected · git
    • e65920661708b7c0f3db45c9cd5d0095034ee37f and later · before 8f3b99c50dd0da1777994ce7c7e60d39b9f60f4baffected · git
    • e65920661708b7c0f3db45c9cd5d0095034ee37f and later · before 5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41faffected · git
    • before 5.12not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-89833Sep 16, 2026 · f2fs: fix to avoid potential deadloop in f2fs_fsync_node_pages()
    0Monitor
  • ← EarlierCVE-2026-89834Sep 16, 2026 · f2fs: fix to migrate all curseg types during free_segment_range
    0Monitor
  • Later →CVE-2026-89836Sep 16, 2026 · f2fs: fix folio_nr_pages() race after put in large folio invalidate
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux22760e3e9cecbddc475edc91600787abf407a302Vendor (CNA)
Linux Linux54196bcfde998fb37009f50e0ef16498f651f0f9Vendor (CNA)
Linux Linux5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41fVendor (CNA)
Linux Linux8f3b99c50dd0da1777994ce7c7e60d39b9f60f4bVendor (CNA)
Linux Linuxa6573f3ffc19542de9ebc1a2b1f930fd48ba538cVendor (CNA)
Linux Linuxaefcec3bebdeed2bff444378122300763325ba23Vendor (CNA)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records