Bug 2492454 (CVE-2026-53026)

Summary:	CVE-2026-53026 kernel: NFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	rhel-process-autobot, smayhew, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's Network File System Daemon (NFSD). An issue with file access counting in the nfsd4_add_rdaccess_to_wrdeleg function can lead to an extra access count for nfs4_file objects. This prevents the proper freeing of associated resources when the NFS server service is stopped. Consequently, this can trigger a system bug during shutdown, potentially leading to a Denial of Service (DoS) condition.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-06-24 18:12:57 UTC

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

NFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg

In nfsd4_add_rdaccess_to_wrdeleg, if fp->fi_fds[O_RDONLY] is already
set by another thread, __nfs4_file_get_access should not be called
to increment the nfs4_file access count since that was already done
by the thread that added READ access to the file. The extra fi_access
count in nfs4_file can prevent the corresponding nfsd_file from being
freed.

When stopping nfs-server service, these extra access counts trigger a
BUG in kmem_cache_destroy() that shows nfsd_file object remaining on
__kmem_cache_shutdown.

This problem can be reproduced by running the Git project's test
suite over NFS.

Comment 1 Mauro Matteo Cascella 2026-06-25 08:31:09 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062453-CVE-2026-53026-0965@gregkh/T

Comment 6 errata-xmlrpc 2026-09-01 07:30:22 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:61887 https://access.redhat.com/errata/RHSA-2026:61887