CVE-2026-90169: ksmbd: free preauth sessions on connection teardown
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: free preauth sessions on connection teardown
SMB3.1.1 multichannel binding preserves the preauthentication hash in a preauthsession between the NTLM negotiate and authenticate requests. The binding NTLM negotiate allocates this object and returns STATUSMOREPROCESSINGREQUIRED. If the client disconnects before it sends the authenticate request, neither the authenticate nor error cleanup paths free the object.
Release any remaining preauthentication sessions when tearing down the connection. Initialize the list when allocating the connection so that this cleanup is safe regardless of the negotiated dialect.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.6.157.1-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.111-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 7.2.6-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.111-1~deb12u1 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.1.191 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.6.157 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.12.110 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.18.52 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 7.2.6 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.113-1~deb12u1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1
Event History
Frequently Asked Questions
Which systems are exposed to this issue?
Systems using the Linux kernel's ksmbd implementation are affected when handling SMB 3.1.1 multichannel binding with NTLM authentication. The issue involves preauthentication sessions created during the binding negotiate phase.
What client behavior triggers the leaked object?
A client initiates a binding NTLM negotiate request, receives STATUS_MORE_PROCESSING_REQUIRED, and then disconnects before sending the authenticate request. In that sequence, the preauthentication session was not released by the existing cleanup paths.