CVE-2026-53390

CVE CVE-2026-53390EUVD EUVD-2026-45512Veröffentlicht 2026-07-19T12:01:54.000ZZuletzt geändert 2026-08-05T12:35:30.000ZCVSS 8.1

Was das Advisory beschreibt

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds read in smb_check_perm_dacl() The permission-check ACE walk in smb_check_perm_dacl() validates the ACE header size and caps sid.num_subauth at SID_MAX_SUB_AUTHORITIES, but it never checks that ace->size is actually large enough to contain num_subauth sub-authorities before compare_sids() dereferences them. CIFS_SID_BASE_SIZE covers the SID header up to but excluding the sub_auth[] array, and offsetof(struct smb_ace, sid) is the ACE header, so the existing guards only guarantee the 8-byte SID base, i.e. zero sub-authorities. compare_sids() then reads ace->sid.sub_auth[i] for i < min(local_sid->num_subauth, ace->sid.num_subauth). The local comparison SIDs (sid_everyone, sid_unix_NFS_mode, and the id_to_sid() result) always have at least one sub-authority, and an attacker controls the ACE revision and authority bytes (which lie within the in-bounds SID base), so they can match one of those SIDs and force the sub_auth read. A crafted ACE with size == 16 and num_subauth >= 1 placed at the tail of the security descriptor therefore causes a heap out-of-bounds read of up to SID_MAX_SUB_AUTHORITIES * sizeof(__le32) bytes past the pntsd allocation. The security descriptor is loaded by ksmbd_vfs_get_sd_xattr() into a buffer sized exactly to the on-disk data (kzalloc(sd_size) in ndr_decode_v4_ntacl()), so the read lands past the allocation. The malformed descriptor can be stored verbatim via SMB2_SET_INFO (the DACL is not normalised before being written to the security.NTACL xattr) and the read fires on a subsequent SMB2_CREATE access check, making this reachable by an authenticated client on a share that uses ACL xattrs. Add the missing num_subauth-versus-ace_size check, mirroring the identical guards already present in the sibling parsers parse_dacl() and smb_inherit_dacl().

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 6.12.84 <6.12.95; 5.15.210 <5.15.212; 151b1799861fde38087c08f613abc2843ef597b0; 6.6.140 <6.6.144; patch: 6.1.177; patch: 6.18.38; 90089584b2e25c4510b7b987387b4405f0673ece <7627ff8c4f9919f14de562b0160ab4ec9d80b1f7; d07b26f39246a82399661936dd0c853983cfade7 <e36e35660adb9b8ef1435ac359151dda5f094c55; patch: 6.12.95; patch: 7.1.3; 95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c <d5c81a095c86fe507c032d08f3a8cfc518444927; f20adc4ef7428bc485ee83fd1a592252fb87718b <988c93d3bba066d8669143e6ec30bb2be9608d53; 282cbbb476b9f35793452bc461934af4c7eca169 <c7488c85fd822959e9b5c22fbd9e7c8a21caf5e0; 325d4ac11f526cb8964cff14548ccf02d8c756d8 <36599894fa8536fefdf1e296c0af71b8b7226859; d07b26f39246a82399661936dd0c853983cfade7 <1ef06004ed4bd6d3ed8c840d9d1a376b66d4935b; 6.18.25 <6.18.38; 7.0.2 <7.1; 6.1.176 <6.1.177; patch: 0; 7.1; patch: 7.2-rc1; patch: 6.6.144; patch: 5.15.212

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.