Answer in brief
CVE-2026-64389 records a High severity (CVSS 8.2) vulnerability in ksmbd: validate NTLMv2 response before updating session key. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.2. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <b56400364aed5c34d6e1a0b493081290a5328a9c || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <89ca7756d5566ba636bb9092cdbe57dab095e136 || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <954d196bebb2b50151cb96454c72dc113b2af1ac | b56400364aed5c34d6e1a0b493081290a5328a9c, 89ca7756d5566ba636bb9092cdbe57dab095e136, 954d196bebb2b50151cb96454c72dc113b2af1ac |
| Linux/Linuxgeneric | 5.15 | Not reported |
| Linux/Linuxgeneric | >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <a6a951416b55eaf51ea2742f7ba786f240e70137 || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <f5d74c186bab26a5d5a025305e67edd0888aa34d || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <b56400364aed5c34d6e1a0b493081290a5328a9c || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <89ca7756d5566ba636bb9092cdbe57dab095e136 || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <954d196bebb2b50151cb96454c72dc113b2af1ac | a6a951416b55eaf51ea2742f7ba786f240e70137, f5d74c186bab26a5d5a025305e67edd0888aa34d, b56400364aed5c34d6e1a0b493081290a5328a9c, 89ca7756d5566ba636bb9092cdbe57dab095e136, 954d196bebb2b50151cb96454c72dc113b2af1ac |
| Linux/Linuxgeneric | >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <e589e997bddde0a6f45672dd871cba7b3ff28e17 || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <a6a951416b55eaf51ea2742f7ba786f240e70137 || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <f5d74c186bab26a5d5a025305e67edd0888aa34d || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <b56400364aed5c34d6e1a0b493081290a5328a9c || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <89ca7756d5566ba636bb9092cdbe57dab095e136 || >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <954d196bebb2b50151cb96454c72dc113b2af1ac | e589e997bddde0a6f45672dd871cba7b3ff28e17, a6a951416b55eaf51ea2742f7ba786f240e70137, f5d74c186bab26a5d5a025305e67edd0888aa34d, b56400364aed5c34d6e1a0b493081290a5328a9c, 89ca7756d5566ba636bb9092cdbe57dab095e136, 954d196bebb2b50151cb96454c72dc113b2af1ac |
Published upstream
Jul 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 30, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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.
Quoted source text, attributed separately from HOL analysis.