Bug 2507082 (CVE-2026-64392)

Summary: CVE-2026-64392 kernel: ksmbd: use opener credentials for delete-on-close
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the ksmbd component of the Linux kernel. This vulnerability allows an attacker to bypass filesystem permission checks during 'delete-on-close' operations. Specifically, when a file handle is torn down, the base-file unlink and extended attribute (xattr) removal operations incorrectly execute with ksmbd worker credentials instead of the original opener's credentials. This can lead to unauthorized deletion of files or removal of extended attributes, potentially compromising data integrity and availability.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-07-25 10:04:02 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ksmbd: use opener credentials for delete-on-close

Delete-on-close can be completed by deferred or durable handle teardown,
where no request work is available. Both the base-file unlink and the ADS
xattr removal consequently run with the ksmbd worker credentials and can
bypass filesystem permission checks.

Run both operations with the credentials captured in struct file when the
handle was opened. This preserves the authenticated user's fsuid, fsgid,
supplementary groups and capability restrictions at final close.
Comment 1 TEJ RATHI 2026-07-30 04:19:57 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072528-CVE-2026-64392-d5b4@gregkh/T