CVE-2026-64389

CVE CVE-2026-64389EUVD EUVD-2026-48933Published 2026-07-25T08:50:36.000ZLast changed 2026-08-05T12:41:26.000ZCVSS 8.2

What the advisory describes

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 arc4_crypt(..., sess->sess_key, ...) -> out_err without expiring the binding session Derive the base session key into a local buffer and copy it to sess->sess_key only after the proof matches. Return immediately on authentication failure so KEY_XCH is only processed after successful authentication.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

Linux — Linux e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <954d196bebb2b50151cb96454c72dc113b2af1ac; patch: 6.18.40; patch: 7.1.4; 5.15; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <b56400364aed5c34d6e1a0b493081290a5328a9c; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <89ca7756d5566ba636bb9092cdbe57dab095e136; patch: 7.2-rc1; patch: 0

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

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Linux — Linux

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