Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for FSCTL mutations SET_SPARSE, SET_ZERO_DATA and SET_COMPRESSION operate on an open SMB handle but call VFS xattr, fallocate or fileattr helpers with the current ksmbd worker credentials. Those helpers can revalidate inode permissions, ownership and LSM policy independently of the SMB handle access mask. Run each operation with the credentials captured in the target file when the handle was opened. Keep credential handling local to these single-file FSCTLs rather than applying session credentials to the complete IOCTL handler, which also contains handle-less and multi-handle operations.
References6
- git.kernel.org/stable/c/1e112c47ec5dd1942e2d4ca6e8e9b712238e20c2
- git.kernel.org/stable/c/a8c18434e1f0d9f7989170bdb0490c0160baf065
- git.kernel.org/stable/c/c6394bcaf254c5baf9aff43376020be5db6d3316
- git.kernel.org/stable/c/cfb2c6f71d61ed807c9d7a7af331d406f1f31877
- git.kernel.org/stable/c/e205f3e7e8c31a47cd11efb6cf663a527177e432
- git.kernel.org/stable/c/fb1cae6302d58414ddf029e3f642711bd30243f7
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H - EPSS — exploit probability
- 1% percentile: 54 · as of 12 November 2026
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