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NVD / CVE Program· CNA Linux

CVE-2026-53392: NFSv4/flexfiles: reject zero filehandle version count

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.52% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 18cc6d57a14fa65ab2a2b52279f549041c4bc9cf, 2131ed64b767ffa8bcdb3677d90f3964e39aabc8, 2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 18cc6d57a14fa65ab2a2b52279f549041c4bc9cf, 2131ed64b767ffa8bcdb3677d90f3964e39aabc8, 2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1 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: NFSv4/flexfiles: reject zero filehandle version count ff_layout_alloc_lseg() decodes the filehandle-version array count from the flexfiles layout body. The value is used as the count for kzalloc_objs(), and the current code only rejects NULL. A zero count yields ZERO_SIZE_PTR, which can be stored in dss_info->fh_versions even though later flexfiles paths assume that at least one filehandle version exists. Reject fh_count == 0 before the allocation, matching the existing zero version_count validation in the flexfiles GETDEVICEINFO parser. A QEMU/KASAN run with a malformed flexfiles layout hit: KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:ff_layout_encode_ff_layoutupdate.isra.0+0x15f/0x750 ff_layout_encode_layoutreturn+0x683/0x970 nfs4_xdr_enc_layoutreturn+0x278/0x3a0 Kernel panic - not syncing: Fatal exception The patched kernel rejects the malformed layout without KASAN/oops/panic, and a valid fh_count=1 regression still opens, reads, and unmounts cleanly.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Jul 19, 2026
Updated
Oct 19, 2026
EPSS
0.5% · 44th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.5
NVD has not scored this yet; the score shown is the CNA’s.

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

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  • 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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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 kernel4.0 and later · before 5.10.261
  • linux linux kernel5.11 and later · before 5.15.212
  • linux linux kernel5.16 and later · before 6.1.178
  • linux linux kernel6.2 and later · before 6.6.145
  • linux linux kernel6.7 and later · before 6.12.96
  • linux linux kernel6.13 and later · before 6.18.38
  • linux linux kernel6.19 and later · before 7.1.3

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

    • 4.0affected
    • d67ae825a59d639e4d8b82413af84d854617a87e and later · before 9033591535c066726f5b505126ccb4068b98fa4faffected · git
    • d67ae825a59d639e4d8b82413af84d854617a87e and later · before 18cc6d57a14fa65ab2a2b52279f549041c4bc9cfaffected · git
    • d67ae825a59d639e4d8b82413af84d854617a87e and later · before be7829715e341b42846437dd9e721005db59f0ccaffected · git
    • d67ae825a59d639e4d8b82413af84d854617a87e and later · before eeabb9020721db6bc132e68eeae380b8d4fb4b04affected · git
    • d67ae825a59d639e4d8b82413af84d854617a87e and later · before 7779c85028a0676fb190cde4f0c540f4f8e97761affected · git
    • d67ae825a59d639e4d8b82413af84d854617a87e and later · before d8c90c7cc061265d5f2813a1f5c82ef2f4707e67affected · git
    • d67ae825a59d639e4d8b82413af84d854617a87e and later · before 2131ed64b767ffa8bcdb3677d90f3964e39aabc8affected · git
    • d67ae825a59d639e4d8b82413af84d854617a87e and later · before 2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2affected · git
    • before 4.0not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2

+96

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-2026-53388Jul 19, 2026 · fuse: re-lock request before replacing page cache folio
    31Monitor
  • ← EarlierCVE-2026-53391Jul 19, 2026 · NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr
    30Monitor
  • Later →CVE-2026-53394Jul 19, 2026 · nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race
    30Monitor

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 Linux18cc6d57a14fa65ab2a2b52279f549041c4bc9cfVendor (CNA)
Linux Linux2131ed64b767ffa8bcdb3677d90f3964e39aabc8Vendor (CNA)
Linux Linux2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2Vendor (CNA)
Linux Linux7779c85028a0676fb190cde4f0c540f4f8e97761Vendor (CNA)
Linux Linux9033591535c066726f5b505126ccb4068b98fa4fVendor (CNA)
Linux Linuxbe7829715e341b42846437dd9e721005db59f0ccVendor (CNA)
Linux Linuxd8c90c7cc061265d5f2813a1f5c82ef2f4707e67Vendor (CNA)
Linux Linuxeeabb9020721db6bc132e68eeae380b8d4fb4b04Vendor (CNA)
azl3 kernel 6.6.144.1-1 on Azure Linux 3.06.6.145.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel-matched6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package registry (OSV)
opensuse:kernel-source7.1.4-1.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)

+8

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

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • 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
Network
Attack complexity
Low
Privileges required
None
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:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

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. SSVC exploitation— → none
  2. 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