CVE-2026-31717

ksmbd: validate owner of durable handle on reconnect

State: Published
Severity: 8.8 High
Published: May 1, 2026
Updated: Aug 5, 2026
Reserved: Mar 9, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: validate owner of durable handle on reconnect

Currently, ksmbd does not verify if the user attempting to reconnect to a durable handle is the same user who originally opened the file. This allows any authenticated user to hijack an orphaned durable handle by predicting or brute-forcing the persistent ID.

According to MS-SMB2, the server MUST verify that the SecurityContext of the reconnect request matches the SecurityContext associated with the existing open. Add a durable_owner structure to ksmbd_file to store the original opener's UID, GID, and account name. and catpure the owner information when a file handle becomes orphaned. and implementing ksmbd_vfs_compare_durable_owner() to validate the identity of the requester during SMB2_CREATE (DHnC).

Scores

CVSS	Score	Vector	Source
3.1	8.8 High	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	8df4bcdb0a4232192b2445256c39b787d58ef14d to before 712cdf917e77a6444ce3836874829d770db20ee6Affected c8efcc786146a951091588e5fa7e3c754850cb3c to before c7f0f0d01c88bdcb8b1694d7d321670013f7ed7dAffected c8efcc786146a951091588e5fa7e3c754850cb3c to before 00ce8d6789dae72d042a4522264964c72891ca37Affected c8efcc786146a951091588e5fa7e3c754850cb3c to before c908c853f304a4969b5aa10eba0b50350cc65b80Affected c8efcc786146a951091588e5fa7e3c754850cb3c to before 49110a8ce654bbe56bef7c5e44cce31f4b102b8aAffected 6.6.32 to before 6.6.142Affected
LinuxLinux	6.9Affected before 6.9Not affected 6.6.142 through 6.6.Not affected 6.12.92 through 6.12.Not affected 6.18.25 through 6.18.Not affected 7.0.2 through 7.0.Not affected 7.1 and laterNot affected

Product

Versions

LinuxLinux

8df4bcdb0a4232192b2445256c39b787d58ef14d to before 712cdf917e77a6444ce3836874829d770db20ee6Affected
c8efcc786146a951091588e5fa7e3c754850cb3c to before c7f0f0d01c88bdcb8b1694d7d321670013f7ed7dAffected
c8efcc786146a951091588e5fa7e3c754850cb3c to before 00ce8d6789dae72d042a4522264964c72891ca37Affected
c8efcc786146a951091588e5fa7e3c754850cb3c to before c908c853f304a4969b5aa10eba0b50350cc65b80Affected
c8efcc786146a951091588e5fa7e3c754850cb3c to before 49110a8ce654bbe56bef7c5e44cce31f4b102b8aAffected
6.6.32 to before 6.6.142Affected

LinuxLinux

6.9Affected
before 6.9Not affected
6.6.142 through 6.6.*Not affected
6.12.92 through 6.12.*Not affected
6.18.25 through 6.18.*Not affected
7.0.2 through 7.0.*Not affected
7.1 and laterNot affected

References

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