CVE-2023-32253Network attack vector

SMB service hang via unreleased crypto contexts

Published Aug 2, 2025 · Updated Jun 29, 2026

Improper resource locking in Linux Kernel ksmbd allows remote attackers to hang the SMB service through concurrent session setup requests. The NTLMv2 authentication paths retain limited crypto contexts across consecutive operations instead of promptly releasing each context for reuse, causing later requests to wait indefinitely. Network access to enabled ksmbd on TCP port 445 is sufficient; successful exploitation stalls SMB request handling without reading or changing data.

CVSS severity5.9
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper resource locking in Linux Kernel ksmbd allows remote attackers to hang the SMB service through concurrent session setup requests. The NTLMv2 authentication paths retain limited crypto contexts across consecutive operations instead of promptly releasing each context for reuse, causing later requests to wait indefinitely. Network access to enabled ksmbd on TCP port 445 is sufficient; successful exploitation stalls SMB request handling without reading or changing data.

The record

CVE
CVE-2023-32253
Published
Aug 2, 2025
Updated
Jun 29, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-413, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 2, 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

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=0 <5.15.112
  2. Affected versionversion=6.0.0 <6.0.*
  3. Affected versionversion=6.1.0 <6.1.28
  4. Affected versionversion=6.2.0 <6.2.15
  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 <5.15.112; version=6.0.0 <6.0.*; version=6.1.0 <6.1.28; version=6.2.0 <6.2.15; version=6.3.0 <6.3.2

Published CVSS scores

5.9Red Hat, Inc.CVSS:3.1/AV:N/AC:H/PR:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-413Improper Resource Locking
T1499.004Endpoint Denial of Service: Application or System Exploitation

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo