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

nfsd: release path refs on follow_down() error

nfsd_cross_mnt() initializes a local struct path with mntget() and
dget() before calling follow_down(). On a negative return the error
arm jumps to out without releasing those references:

err = follow_down(&path, follow_flags);
if (err < 0)
goto out;

follow_down() never drops the caller's entry-time refs on any error
sub-case; for example a pre-cross d_manage() failure leaves path
untouched, so the mntget()/dget() taken on entry survive the call.

Every other early-exit arm in nfsd_cross_mnt() (other-namespace
return, IS_ERR(exp2), and the success tail after the swap) already
calls path_put(&path); the err < 0 arm is the lone omission. The
leak inflates mnt_count and d_count on each failed cross-mount,
blocking umount and pinning dentries against the shrinker, and is
reachable by any authenticated NFS client through nfsd_lookup_dentry
or the NFSv4 READDIR encode path.

Fix by calling path_put(&path) before the goto out in the err < 0
arm so the entry-time refs are released on all follow_down() error
returns.
Published: 2026-09-11
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

Sat, 12 Sep 2026 08:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-401
CWE-668

Fri, 11 Sep 2026 23:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: nfsd: release path refs on follow_down() error nfsd_cross_mnt() initializes a local struct path with mntget() and dget() before calling follow_down(). On a negative return the error arm jumps to out without releasing those references: err = follow_down(&path, follow_flags); if (err < 0) goto out; follow_down() never drops the caller's entry-time refs on any error sub-case; for example a pre-cross d_manage() failure leaves path untouched, so the mntget()/dget() taken on entry survive the call. Every other early-exit arm in nfsd_cross_mnt() (other-namespace return, IS_ERR(exp2), and the success tail after the swap) already calls path_put(&path); the err < 0 arm is the lone omission. The leak inflates mnt_count and d_count on each failed cross-mount, blocking umount and pinning dentries against the shrinker, and is reachable by any authenticated NFS client through nfsd_lookup_dentry or the NFSv4 READDIR encode path. Fix by calling path_put(&path) before the goto out in the err < 0 arm so the entry-time refs are released on all follow_down() error returns.
Title nfsd: release path refs on follow_down() error
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-11T19:46:23.293Z

Reserved: 2026-09-11T19:38:34.751Z

Link: CVE-2026-89707

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-11T20:19:58.017

Modified: 2026-09-11T20:19:58.017

Link: CVE-2026-89707

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-12T08:15:07Z

Weaknesses