CVE-2026-64398

CVE CVE-2026-64398EUVD EUVD-2026-48942Published 2026-07-25T08:50:42.000ZLast changed 2026-08-05T12:41:36.000ZCVSS 8.1

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: ksmbd: add a permission check for FSCTL_SET_ZERO_DATA FSCTL_SET_ZERO_DATA in smb2_ioctl() destroys file data via ksmbd_vfs_zero_data() -> vfs_fallocate(PUNCH_HOLE/ZERO_RANGE) after checking only the share-level KSMBD_TREE_CONN_FLAG_WRITABLE, with no per-handle access check. A handle opened with only FILE_WRITE_ATTRIBUTES still yields an FMODE_WRITE filp (FILE_WRITE_ATTRIBUTES is part of FILE_WRITE_DESIRE_ACCESS_LE, so smb2_create_open_flags() opens it O_WRONLY), so the vfs_fallocate FMODE_WRITE check does not stop it; only the missing fp->daccess gate would. Reproduced on mainline 7.1-rc7 with KASAN by an authenticated SMB client: a FILE_WRITE_ATTRIBUTES-only handle zeroed 4096 bytes of file data it had no FILE_WRITE_DATA right to (6/6; a FILE_READ_DATA-only handle was correctly denied). This is the unfixed sibling of commit cc57232cae23 ("ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE"). Because SET_ZERO_DATA writes data (not an attribute), require FILE_WRITE_DATA.

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 patch: 6.1.178; patch: 6.12.96; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <deffa929086d7902e30918adf3dd27ccfe9c08b1; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <3072d82461f498c85daea8766e9d8bfbada31605; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <3320ba068198adc144c89d6661b805acce01735b; patch: 6.6.145; patch: 7.2-rc1; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <ca53bb17f4e8232cfaece3953d3cef62c559b039; 5.15; patch: 6.18.39; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <57f2042fd87d7ce8fc3ac8b6c176e554df68b1a7; patch: 0; patch: 7.1.4; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <25377f369688dd0bd814dc8965ed26d44238ecaa

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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