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NVD / CVE Program· CNA Linux

CVE-2026-23230: smb: client: split cached_fid bitfields to avoid shared-byte RMW races

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: 0.27% (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 3eaa22d688311c708b73f3c68bc6d0c8e3f0f77a, 4386f6af8aaedd0c5ad6f659b40cadcc8f423828, 4cfa4c37dcbcfd70866e856200ed8a2894cac578.
  • Severity is disputed: the assigning authority (CNA) scores it 8.8, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 3eaa22d688311c708b73f3c68bc6d0c8e3f0f77a, 4386f6af8aaedd0c5ad6f659b40cadcc8f423828, 4cfa4c37dcbcfd70866e856200ed8a2894cac578 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: smb: client: split cached_fid bitfields to avoid shared-byte RMW races is_open, has_lease and on_list are stored in the same bitfield byte in struct cached_fid but are updated in different code paths that may run concurrently. Bitfield assignments generate byte read–modify–write operations (e.g. `orb $mask, addr` on x86_64), so updating one flag can restore stale values of the others. A possible interleaving is: CPU1: load old byte (has_lease=1, on_list=1) CPU2: clear both flags (store 0) CPU1: RMW store (old | IS_OPEN) -> reintroduces cleared bits To avoid this class of races, convert these flags to separate bool fields.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Feb 18, 2026
Updated
Oct 19, 2026
EPSS
0.2% · 20th 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 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
8.8
3.3 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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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Follow CVE-2026-23230

When you'll hear from us

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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 kernel6.1 and later · before 6.1.164
  • linux linux kernel6.2 and later · before 6.6.125
  • linux linux kernel6.7 and later · before 6.12.72
  • linux linux kernel6.13 and later · before 6.18.11
  • linux linux kernel6.19 and later · before 6.19.1

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

    • 6.1affected
    • ebe98f1447bbccf8228335c62d86af02a0ed23f7 and later · before 569fecc56bfe4df66f05734d67daef887746656baffected · git
    • ebe98f1447bbccf8228335c62d86af02a0ed23f7 and later · before 4386f6af8aaedd0c5ad6f659b40cadcc8f423828affected · git
    • ebe98f1447bbccf8228335c62d86af02a0ed23f7 and later · before 3eaa22d688311c708b73f3c68bc6d0c8e3f0f77aaffected · git
    • ebe98f1447bbccf8228335c62d86af02a0ed23f7 and later · before c4b9edd55987384a1f201d3d07ff71e448d79c1baffected · git
    • ebe98f1447bbccf8228335c62d86af02a0ed23f7 and later · before 4cfa4c37dcbcfd70866e856200ed8a2894cac578affected · git
    • ebe98f1447bbccf8228335c62d86af02a0ed23f7 and later · before ec306600d5ba7148c9dbf8f5a8f1f5c1a044a241affected · git
    • before 6.1not affected · semver
    • 6.1.164 and later · up to and including 6.1.*not affected · semver
    • 6.6.125 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:12linuxbefore 6.1.164-16.1.164-1
Debian:13linuxbefore 6.12.73-16.12.73-1
Debian:14linuxbefore 6.18.12-16.18.12-1
SUSE:Linux Enterprise Live Patching 15 SP6kernel-defaultbefore 6.4.0-150600.23.135.16.4.0-150600.23.135.1
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6_Update_31before 1-150600.13.3.41-150600.13.3.4
SUSE:Linux Enterprise Live Patching 15 SP7kernel-livepatch-SLE15-SP7_Update_21before 1-150700.15.3.11-150700.15.3.1
SUSE:Linux Enterprise Live Patching 15 SP7kernel-livepatch-SLE15-SP7-RT_Update_20before 1-150700.1.3.11-150700.1.3.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-64kbbefore 6.4.0-150700.53.81.16.4.0-150700.53.81.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-defaultbefore 6.4.0-150700.53.81.16.4.0-150700.53.81.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-default-basebefore 6.4.0-150700.53.81.1.150700.17.45.16.4.0-150700.53.81.1.150700.17.45.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-sourcebefore 6.4.0-150700.53.81.16.4.0-150700.53.81.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-zfcpdumpbefore 6.4.0-150700.53.81.16.4.0-150700.53.81.1
SUSE:Linux Enterprise Module for Development Tools 15 SP7kernel-docsbefore 6.4.0-150700.53.81.16.4.0-150700.53.81.1
SUSE:Linux Enterprise Module for Development Tools 15 SP7kernel-obs-buildbefore 6.4.0-150700.53.81.16.4.0-150700.53.81.1
SUSE:Linux Enterprise Module for Development Tools 15 SP7kernel-symsbefore 6.4.0-150700.53.81.16.4.0-150700.53.81.1
SUSE:Linux Enterprise Module for Public Cloud 15 SP7kernel-azurebefore 6.4.0-150700.53.81.16.4.0-150700.53.81.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-64kbbefore 6.4.0-150600.23.135.16.4.0-150600.23.135.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-default-basebefore 6.4.0-150600.23.135.1.150600.12.62.46.4.0-150600.23.135.1.150600.12.62.4
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-docsbefore 6.4.0-150600.23.135.16.4.0-150600.23.135.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-obs-buildbefore 6.4.0-150600.23.135.16.4.0-150600.23.135.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-sourcebefore 6.4.0-150600.23.135.16.4.0-150600.23.135.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-symsbefore 6.4.0-150600.23.135.16.4.0-150600.23.135.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-zfcpdumpbefore 6.4.0-150600.23.135.16.4.0-150600.23.135.1
SUSE:Linux Micro 6.0kernel-defaultbefore 6.4.0-52.16.4.0-52.1

+9

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-2026-23223Feb 18, 2026 · xfs: fix UAF in xchk_btree_check_block_owner
    31Monitor
  • ← EarlierCVE-2026-23226Feb 18, 2026 · ksmbd: add chann_lock to protect ksmbd_chann_list xarray
    31Monitor
  • Later →CVE-2026-23232Mar 4, 2026 · Revert "f2fs: block cache/dio write during f2fs_enable_checkpoint()"
    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 Linux3eaa22d688311c708b73f3c68bc6d0c8e3f0f77aVendor (CNA)
Linux Linux4386f6af8aaedd0c5ad6f659b40cadcc8f423828Vendor (CNA)
Linux Linux4cfa4c37dcbcfd70866e856200ed8a2894cac578Vendor (CNA)
Linux Linux569fecc56bfe4df66f05734d67daef887746656bVendor (CNA)
Linux Linuxc4b9edd55987384a1f201d3d07ff71e448d79c1bVendor (CNA)
Linux Linuxec306600d5ba7148c9dbf8f5a8f1f5c1a044a241Vendor (CNA)
debian:linux6.1.164-1 · Debian:12Package registry (OSV)
suse:kernel-64kb6.4.0-150700.53.81.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP7Package registry (OSV)
suse:kernel-default6.4.0-52.1 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:kernel-default-base6.4.0-52.1.21.36 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:kernel-docs6.4.0-150700.53.81.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP7Package registry (OSV)
suse:kernel-kvmsmall6.4.0-52.1 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:kernel-livepatch-SLE15-SP7-RT_Update_201-150700.1.3.1 · SUSE:Linux Enterprise Live Patching 15 SP7Package registry (OSV)
suse:kernel-obs-build6.4.0-150700.53.81.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP7Package registry (OSV)
suse:kernel-rt6.4.0-52.1 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:kernel-source6.4.0-52.1 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:kernel-source-rt6.4.0-52.1 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:kernel-syms-rt6.4.0-150700.7.75.1 · SUSE:Real Time Module 15 SP7Package registry (OSV)
suse:kernel-zfcpdump6.4.0-150700.53.81.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP7Package 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-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

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.

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (6 more)

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

All records