CVE-2026-31717: high-severity vulnerability in Linux
ksmbd: validate owner of durable handle on reconnect
Published · Updated
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.8epss 0.6%
exploitation probability
0.6%top 53% of all CVEs
observed exploitation
nono source reports it
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).
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected products
Linux · LinuxRelated CVEs — Linux
In the same product, most dangerous first.
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References
https://git.kernel.org/stable/c/00ce8d6789dae72d042a4522264964c72891ca37https://git.kernel.org/stable/c/49110a8ce654bbe56bef7c5e44cce31f4b102b8ahttps://git.kernel.org/stable/c/712cdf917e77a6444ce3836874829d770db20ee6https://git.kernel.org/stable/c/c7f0f0d01c88bdcb8b1694d7d321670013f7ed7dhttps://git.kernel.org/stable/c/c908c853f304a4969b5aa10eba0b50350cc65b80