CVE-2026-64389
8.2 · HIGHOverview
CVE-2026-64389 is a high-severity vulnerability. It was published on July 25, 2026 and has a CVSS 3.1 base score of 8.2 (HIGH).
This vulnerability has a CVSS 3.1 base score of 8.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: validate NTLMv2 response before updating session key
ksmbd_auth_ntlmv2() derives the NTLMv2 session key into
sess->sess_key before it verifies the NTLMv2 response.
ksmbd_decode_ntlmssp_auth_blob() then continues into KEY_XCH even
when ksmbd_auth_ntlmv2() failed.
With SMB3 multichannel binding, the failed authentication operates on
an existing session and the session setup error path does not expire
binding sessions. A client can send a binding session setup with a
bad NT proof and KEY_XCH and still modify sess->sess_key before
STATUS_LOGON_FAILURE is returned.
Relevant path:
smb2_sess_setup()
-> conn->binding = true
-> ntlm_authenticate()
-> session_user()
-> ksmbd_decode_ntlmssp_auth_blob()
-> ksmbd_auth_ntlmv2()
-> calc_ntlmv2_hash()
-> hmac_md5_usingrawkey(..., sess->sess_key)
-> crypto_memneq() returns mismatch
-> KEY_XCH
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Frequently Asked Questions
What is CVE-2026-64389?
CVE-2026-64389 is a high-severity vulnerability. It was published on July 25, 2026 and has a CVSS 3.1 base score of 8.2 (HIGH).
How severe is CVE-2026-64389?
This vulnerability has a CVSS 3.1 base score of 8.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-64389?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-64389?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-64389 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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