CVE-2026-53383

CVE CVE-2026-53383EUVD EUVD-2026-45505Veröffentlicht 2026-07-19T11:59:31.000ZZuletzt geändert 2026-08-05T12:35:22.000ZCVSS 7.5

Was das Advisory beschreibt

In the Linux kernel, the following vulnerability has been resolved: ksmbd: reject non-VALID session in compound request branch smb2_check_user_session() takes a shortcut for any operation that is not the first in a COMPOUND request: it reuses work->sess (the session bound by the first operation) and validates only the SessionId, then returns "valid". It never re-checks work->sess->state == SMB2_SESSION_VALID, and a SessionId of 0xFFFFFFFFFFFFFFFF (ULLONG_MAX, the MS-SMB2 related-operation value) skips even the id comparison. The standalone path (ksmbd_session_lookup_all() plus the SESSION_SETUP state machine) does enforce the VALID state; the compound branch bypasses all of it. A SESSION_SETUP carrying only an NTLM Type-1 (NtLmNegotiate) blob publishes a fresh SMB2_SESSION_IN_PROGRESS session whose sess->user is still NULL (->user is assigned later, by ntlm_authenticate()). Used as operation 1 of a COMPOUND with operation 2 = TREE_CONNECT (related, SessionId=ULLONG_MAX, \\host\IPC$), the tree-connect then runs on that IN_PROGRESS session and reaches ksmbd_ipc_tree_connect_request(), which dereferences user_name(sess->user) with sess->user == NULL (transport_ipc.c:687/701/704) -> remote NULL-pointer dereference and a kernel Oops that wedges the ksmbd worker for all clients. Reject any non-first compound operation that lands on a session which is not SMB2_SESSION_VALID, mirroring the validity the standalone lookup path enforces. SESSION_SETUP itself legitimately runs on an IN_PROGRESS session, but it is never carried as a non-first compound operation, so multi-leg authentication is unaffected by this check.

Quelle: EUVD (ENISA), im Wortlaut der Meldung.

Produkte, die das Advisory nennt

Diese Angaben stammen aus der Meldung selbst, nicht aus einer Prüfung durch uns.

• Linux — Linux patch: 6.6.144; 854156d12caa9d36de1cf5f084591c7686cc8a9d <fc578523a72cb8b329d32070b95898e81613cc3f; patch: 0; 6.1.36 <6.1.177; patch: 7.0.14; 5005bcb4219156f1bf7587b185080ec1da08518e <d2bbbb6c55812220fee5d801c275cc267ea3cbeb; eb947403518ea3d93f6d89264bb1f5416bb0c7d0 <25ff12b82a376ff5c4583102a63d2456a6b9ebb9; 5.15.121 <5.15.211; 5005bcb4219156f1bf7587b185080ec1da08518e <8f0302fb691537d33ec8f668565257ea9d340ffe; patch: 7.1.2; patch: 6.1.177; 5005bcb4219156f1bf7587b185080ec1da08518e <609ca17d869d04ba249e32cdcbf13c0b1c66f43c; 6.3.10 <6.4; 5005bcb4219156f1bf7587b185080ec1da08518e <7cad3ceaf679c55bc9946685dacafce78ce6b51a; patch: 6.18.37; patch: 7.2-rc1; patch: 6.12.95; 5005bcb4219156f1bf7587b185080ec1da08518e <06e1f05a1dbe8bbd054c0927b17fc0a61cc8bef7; d1066c1b3663401cd23c0d6e60cdae750ce00c0f; 5005bcb4219156f1bf7587b185080ec1da08518e <5f983b864d3d473ac533b2f4f44a1bbe5dcbccf4; patch: 5.15.211; 6.4

Die genannten Versionen sind die Angabe der Meldung. Patchlage vergleicht keine Versionsnummern und leitet aus ihnen keine Aussage ab — welche Version installiert ist, muss ein Mensch nachsehen.

Im Produktkatalog geführt

Für diese Produkte kann ein Bestand in Patchlage erfasst werden. Ein Advisory dazu erscheint am Morgen danach im Lagebericht.

• Linux — Linux

Patchlage meldet Treffer und Verdachtsfälle. Zu allem anderen sagt dieses System nichts — weder diese Seite noch der Lagebericht behauptet je, dass ein Bestand sicher ist.