CVE-2026-31717

HIGH

ksmbd: validate owner of durable handle on reconnect

Title source: cna
STIX 2.1

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).

Exploits (1)

nomisec WORKING POC
by TurtleARM · poc
https://github.com/TurtleARM/CVE-2026-31717-KSMBD-Exploit

Scores

CVSS v3 8.8
EPSS 0.0004
EPSS Percentile 11.9%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Details

Status published
Products (9)
Linux/Linux < 6.9
Linux/Linux 6.18.25 - 6.18.*
Linux/Linux 6.9
Linux/Linux 7.0.2 - 7.0.*
Linux/Linux 7.1-rc1
Linux/Linux 8df4bcdb0a4232192b2445256c39b787d58ef14d
Linux/Linux c8efcc786146a951091588e5fa7e3c754850cb3c - 00ce8d6789dae72d042a4522264964c72891ca37
Linux/Linux c8efcc786146a951091588e5fa7e3c754850cb3c - 49110a8ce654bbe56bef7c5e44cce31f4b102b8a
Linux/Linux c8efcc786146a951091588e5fa7e3c754850cb3c - c908c853f304a4969b5aa10eba0b50350cc65b80
Published May 01, 2026
Tracked Since May 01, 2026