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NVD / CVE Program· CNA Linux

CVE-2023-53440: nilfs2: fix sysfs interface lifetime

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.15% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 1942ccb7d95f287a312fcbabfa8bc9ba501b1953, 3dbee84bf9e3273c4bb9ca6fc18ff22fba23dd24, 42560f9c92cc43dce75dbf06cc0d840dced39b12.
  • Severity is disputed: the assigning authority (CNA) scores it 7.8, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 1942ccb7d95f287a312fcbabfa8bc9ba501b1953, 3dbee84bf9e3273c4bb9ca6fc18ff22fba23dd24, 42560f9c92cc43dce75dbf06cc0d840dced39b12 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: nilfs2: fix sysfs interface lifetime The current nilfs2 sysfs support has issues with the timing of creation and deletion of sysfs entries, potentially leading to null pointer dereferences, use-after-free, and lockdep warnings. Some of the sysfs attributes for nilfs2 per-filesystem instance refer to metadata file "cpfile", "sufile", or "dat", but nilfs_sysfs_create_device_group that creates those attributes is executed before the inodes for these metadata files are loaded, and nilfs_sysfs_delete_device_group which deletes these sysfs entries is called after releasing their metadata file inodes. Therefore, access to some of these sysfs attributes may occur outside of the lifetime of these metadata files, resulting in inode NULL pointer dereferences or use-after-free. In addition, the call to nilfs_sysfs_create_device_group() is made during the locking period of the semaphore "ns_sem" of nilfs object, so the shrinker call caused by the memory allocation for the sysfs entries, may derive lock dependencies "ns_sem" -> (shrinker) -> "locks acquired in nilfs_evict_inode()". Since nilfs2 may acquire "ns_sem" deep in the call stack holding other locks via its error handler __nilfs_error(), this causes lockdep to report circular locking. This is a false positive and no circular locking actually occurs as no inodes exist yet when nilfs_sysfs_create_device_group() is called. Fortunately, the lockdep warnings can be resolved by simply moving the call to nilfs_sysfs_create_device_group() out of "ns_sem". This fixes these sysfs issues by revising where the device's sysfs interface is created/deleted and keeping its lifetime within the lifetime of the metadata files above.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Sep 18, 2025
Updated
Aug 5, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
7.8
2.3 point gap

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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 you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel3.17 and later · before 4.14.313
  • linux linux kernel4.15 and later · before 4.19.281
  • linux linux kernel4.20 and later · before 5.4.241
  • linux linux kernel5.5 and later · before 5.10.178
  • linux linux kernel5.11 and later · before 5.15.107
  • linux linux kernel5.16 and later · before 6.1.24
  • linux linux kernel6.2 and later · before 6.2.11
  • linux linux kernel6.3

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

    • 3.17affected
    • dd70edbde2627f47df118d899de6bbb55abcfdbf and later · before d20dcec8f326deb77b6688f8441e014045dac457affected · git
    • dd70edbde2627f47df118d899de6bbb55abcfdbf and later · before 5fe0ea141fbb887d407f1bf572ebf24427480d5caffected · git
    • dd70edbde2627f47df118d899de6bbb55abcfdbf and later · before 83b16a60e413148685739635901937e2f16a7873affected · git
    • dd70edbde2627f47df118d899de6bbb55abcfdbf and later · before 3dbee84bf9e3273c4bb9ca6fc18ff22fba23dd24affected · git
    • dd70edbde2627f47df118d899de6bbb55abcfdbf and later · before d540aea451ab5489777a8156560f1388449b3109affected · git
    • dd70edbde2627f47df118d899de6bbb55abcfdbf and later · before 1942ccb7d95f287a312fcbabfa8bc9ba501b1953affected · git
    • dd70edbde2627f47df118d899de6bbb55abcfdbf and later · before daf4eb3a908b108279b60172d2f176e70d2df875affected · git
    • dd70edbde2627f47df118d899de6bbb55abcfdbf and later · before 42560f9c92cc43dce75dbf06cc0d840dced39b12affected · git
    • before 3.17not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.25-16.1.25-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2023-53438Sep 18, 2025 · x86/MCE: Always save CS register on AMD Zen IF Poison errors
    22Monitor
  • ← EarlierCVE-2023-53439Sep 18, 2025 · net: skb_partial_csum_set() fix against transport header magic value
    22Monitor
  • Later →CVE-2023-53441Sep 18, 2025 · bpf: cpumap: Fix memory leak in cpu_map_update_elem
    22Monitor

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 Linux1942ccb7d95f287a312fcbabfa8bc9ba501b1953Vendor (CNA)
Linux Linux3dbee84bf9e3273c4bb9ca6fc18ff22fba23dd24Vendor (CNA)
Linux Linux42560f9c92cc43dce75dbf06cc0d840dced39b12Vendor (CNA)
Linux Linux5fe0ea141fbb887d407f1bf572ebf24427480d5cVendor (CNA)
Linux Linux83b16a60e413148685739635901937e2f16a7873Vendor (CNA)
Linux Linuxd20dcec8f326deb77b6688f8441e014045dac457Vendor (CNA)
Linux Linuxd540aea451ab5489777a8156560f1388449b3109Vendor (CNA)
Linux Linuxdaf4eb3a908b108279b60172d2f176e70d2df875Vendor (CNA)
debian:linux6.1.25-1 · 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.

No history yet (it accumulates with the daily EPSS job).

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).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

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✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

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

All records