CVE-2023-32256Network attack vector

Kernel-data disclosure via multichannel session race

Published Aug 1, 2025 · Updated Jun 29, 2026

Use-after-free in ksmbd on affected Linux Kernel releases allows remote attackers to disclose kernel data over SMB. SMB2 logoff frees a tree connection while a concurrent SMB2_QUERY_INFO or close request on another channel can still dereference it because teardown does not wait for every channel request. Only systems with ksmbd enabled are exposed; unauthenticated network access to SMB is sufficient, and exploitation can disclose memory or crash the kernel.

CVSS severity7.5
High
EPSS probability0.53%
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 ksmbd on affected Linux Kernel releases allows remote attackers to disclose kernel data over SMB. SMB2 logoff frees a tree connection while a concurrent SMB2_QUERY_INFO or close request on another channel can still dereference it because teardown does not wait for every channel request. Only systems with ksmbd enabled are exposed; unauthenticated network access to SMB is sufficient, and exploitation can disclose memory or crash the kernel.

The record

CVE
CVE-2023-32256
Published
Aug 1, 2025
Updated
Jun 29, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-421, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=0 <5.15.145
  2. Affected versionversion=6.0.0 <6.0.*
  3. Affected versionversion=6.1.0 <6.1.29
  4. Affected versionversion=6.2.0 <6.2.16
  5. Affected versionversion=6.3.0 <6.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0 <5.15.145; version=6.0.0 <6.0.*; version=6.1.0 <6.1.29; version=6.2.0 <6.2.16; version=6.3.0 <6.3.2

Published CVSS scores

7.5Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/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

CWE-421Race Condition During Access to Alternate Channel
T1210Exploitation of Remote Services

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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