CVE-2025-40328Network attack vector

Memory corruption via cached-directory reference-count race

Published Dec 9, 2025 · Updated Aug 5, 2026

Use-after-free in the Linux kernel SMB client allows remote attackers to corrupt memory through a cached-directory reference-count race. A timing gap lets find_or_create_cached_dir() acquire a cached_fid reference after kref_put() reduces its count to zero but before smb2_close_cached_fid() takes cfid_list_lock. Exploitation requires an attacker-controlled or intercepted SMB server and routine directory activity on its mounted share; successful reuse can disclose or modify kernel memory or panic the host.

CVSS severity8.8
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel SMB client allows remote attackers to corrupt memory through a cached-directory reference-count race. A timing gap lets find_or_create_cached_dir() acquire a cached_fid reference after kref_put() reduces its count to zero but before smb2_close_cached_fid() takes cfid_list_lock. Exploitation requires an attacker-controlled or intercepted SMB server and routine directory activity on its mounted share; successful reuse can disclose or modify kernel memory or panic the host.

The record

CVE
CVE-2025-40328
Published
Dec 9, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.1
  2. Affected versionversion=ebe98f1447bbccf8228335c62d86af02a0ed23f7 <065bd62412271a2d734810dd50336cae88c54427
  3. Affected versionversion=ebe98f1447bbccf8228335c62d86af02a0ed23f7 <734e99623c5b65bf2c03e35978a0b980ebc3c2f8
  4. Affected versionversion=ebe98f1447bbccf8228335c62d86af02a0ed23f7 <bdb596ceb4b7c3f28786a33840263728217fbcf5
  5. Affected versionversion=ebe98f1447bbccf8228335c62d86af02a0ed23f7 <cb52d9c86d70298de0ab7c7953653898cbc0efd6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.1; version=ebe98f1447bbccf8228335c62d86af02a0ed23f7 <065bd62412271a2d734810dd50336cae88c54427; version=ebe98f1447bbccf8228335c62d86af02a0ed23f7 <734e99623c5b65bf2c03e35978a0b980ebc3c2f8; version=ebe98f1447bbccf8228335c62d86af02a0ed23f7 <bdb596ceb4b7c3f28786a33840263728217fbcf5; version=ebe98f1447bbccf8228335c62d86af02a0ed23f7 <cb52d9c86d70298de0ab7c7953653898cbc0efd6

Published CVSS scores

7.0Oracle LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
8.8Linux Kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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