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NVD / CVE Program· CNA Linux

CVE-2025-38523: cifs: Fix the smbd_response slab to allow usercopy

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: 0.36% (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 43e7e284fc77b710d899569360ea46fa3374ae22, 87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4, f0dd353d47f7051afa98c6c60c7486831eb1a410.
  • Severity is disputed: the assigning authority (CNA) scores it 7.5, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 43e7e284fc77b710d899569360ea46fa3374ae22, 87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4, f0dd353d47f7051afa98c6c60c7486831eb1a410 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: cifs: Fix the smbd_response slab to allow usercopy The handling of received data in the smbdirect client code involves using copy_to_iter() to copy data from the smbd_reponse struct's packet trailer to a folioq buffer provided by netfslib that encapsulates a chunk of pagecache. If, however, CONFIG_HARDENED_USERCOPY=y, this will result in the checks then performed in copy_to_iter() oopsing with something like the following: CIFS: Attempting to mount //172.31.9.1/test CIFS: VFS: RDMA transport established usercopy: Kernel memory exposure attempt detected from SLUB object 'smbd_response_0000000091e24ea1' (offset 81, size 63)! ------------[ cut here ]------------ kernel BUG at mm/usercopy.c:102! ... RIP: 0010:usercopy_abort+0x6c/0x80 ... Call Trace: <TASK> __check_heap_object+0xe3/0x120 __check_object_size+0x4dc/0x6d0 smbd_recv+0x77f/0xfe0 [cifs] cifs_readv_from_socket+0x276/0x8f0 [cifs] cifs_read_from_socket+0xcd/0x120 [cifs] cifs_demultiplex_thread+0x7e9/0x2d50 [cifs] kthread+0x396/0x830 ret_from_fork+0x2b8/0x3b0 ret_from_fork_asm+0x1a/0x30 The problem is that the smbd_response slab's packet field isn't marked as being permitted for usercopy. Fix this by passing parameters to kmem_slab_create() to indicate that copy_to_iter() is permitted from the packet region of the smbd_response slab objects, less the header space.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Aug 16, 2025
Updated
Aug 5, 2026
EPSS
0.3% · 30th 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 · 0.3%

CNA vs NVD score

NVD
5.5
CNA · Linux
7.5
2.0 point gap

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

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

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  • 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 kernel6.12 and later · before 6.12.36
  • linux linux kernel6.13 and later · before 6.15.8
  • linux linux kernel6.16

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

    • 6.12affected
    • ee4cdf7ba857a894ad1650d6ab77669cbbfa329e and later · before 87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4affected · git
    • ee4cdf7ba857a894ad1650d6ab77669cbbfa329e and later · before f0dd353d47f7051afa98c6c60c7486831eb1a410affected · git
    • ee4cdf7ba857a894ad1650d6ab77669cbbfa329e and later · before 43e7e284fc77b710d899569360ea46fa3374ae22affected · git
    • before 6.12not affected · semver
    • 6.12.36 and later · up to and including 6.12.*not affected · semver
    • 6.15.8 and later · up to and including 6.15.*not affected · semver
    • 6.16 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-55.37.1.el10_06.12.0-55.37.1.el10_0
AlmaLinux:10kernel-docbefore 6.12.0-55.37.1.el10_06.12.0-55.37.1.el10_0
Debian:13linuxbefore 6.12.37-16.12.37-1
Red Hat:enterprise_linux:10.0kernelbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64kbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-corebefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debugbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debug-corebefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debug-debuginfobefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debug-develbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debug-devel-matchedbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debug-modulesbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debug-modules-corebefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debug-modules-extrabefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-debuginfobefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-develbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-devel-matchedbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-modulesbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-modules-corebefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-64k-modules-extrabefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-abi-stablelistsbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-corebefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-debugbefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0
Red Hat:enterprise_linux:10.0kernel-debug-corebefore 0:6.12.0-55.37.1.el10_00:6.12.0-55.37.1.el10_0

+71

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-2025-38521Aug 16, 2025 · drm/imagination: Fix kernel crash when hard resetting the GPU
    28Monitor
  • ← EarlierCVE-2025-38522Aug 16, 2025 · sched/ext: Prevent update_locked_rq() calls with NULL rq
    22Monitor
  • Later →CVE-2025-38525Aug 16, 2025 · rxrpc: Fix irq-disabled in local_bh_enable()
    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 Linux43e7e284fc77b710d899569360ea46fa3374ae22Vendor (CNA)
Linux Linux87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4Vendor (CNA)
Linux Linuxf0dd353d47f7051afa98c6c60c7486831eb1a410Vendor (CNA)
almalinux:kernel-abi-stablelists6.12.0-55.37.1.el10_0 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-doc6.12.0-55.37.1.el10_0 · AlmaLinux:10Package registry (OSV)
debian:linux6.12.37-1 · Debian:13Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-devel-matched0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debuginfo0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debuginfo-common-aarch640:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debuginfo-common-ppc64le0:6.12.0-55.37.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
rocky linux:kernel0:6.12.0-55.37.1.el10_0 · Rocky Linux:10Package 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.

  • CVE-2022-49099171 days apartDrivers: hv: vmbus: Fix initialization of device object in vmbus_device_register()
    22Monitor
  • CVE-2021-47343452 days apartdm btree remove: assign new_root only when removal succeeds
    22Monitor

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-1188 · Initialization of a Resource with an Insecure Default

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.

Change log

  1. Fix✗ → ✓

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

References

Show all references (2 more)

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

All records