CVE-2023-32249Network attack vector

Unauthenticated session hijacking via guest multichannel binding

Published Aug 16, 2025 · Updated Aug 15, 2026

Improper authentication in affected Linux kernel releases allows remote attackers to hijack live ksmbd SMB sessions. The SMB2 SESSION_SETUP multichannel path performs a global Session ID lookup and accepts guest reauthentication without isolating the requested session. KSMBD must be enabled and a victim session must be active; successful binding grants that session's read, create, modify, and delete rights.

CVSS severity9.1
Critical
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in affected Linux kernel releases allows remote attackers to hijack live ksmbd SMB sessions. The SMB2 SESSION_SETUP multichannel path performs a global Session ID lookup and accepts guest reauthentication without isolating the requested session. KSMBD must be enabled and a victim session must be active; successful binding grants that session's read, create, modify, and delete rights.

The record

CVE
CVE-2023-32249
Published
Aug 16, 2025
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1563
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 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=5.15
  2. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <088131b7b01099720a528a72005ff17868705d40
  3. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <1f0490586544455e5be698be2e6c30077b4ec461
  4. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <3353ab2df5f68dab7da8d5ebb427a2d265a1f2b2
  5. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <4a98e859c4673013385a54084e0cd865695ca072
  6. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <ed76d3a8910be06cd4e4ba63bf6075bf903945a1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.15; version=f5a544e3bab78142207e0242d22442db85ba1eff <088131b7b01099720a528a72005ff17868705d40; version=f5a544e3bab78142207e0242d22442db85ba1eff <1f0490586544455e5be698be2e6c30077b4ec461; version=f5a544e3bab78142207e0242d22442db85ba1eff <3353ab2df5f68dab7da8d5ebb427a2d265a1f2b2; version=f5a544e3bab78142207e0242d22442db85ba1eff <4a98e859c4673013385a54084e0cd865695ca072; version=f5a544e3bab78142207e0242d22442db85ba1eff <ed76d3a8910be06cd4e4ba63bf6075bf903945a1

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.5Zero Day InitiativeCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
9.1kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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.

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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

T1563Remote Service Session Hijacking

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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