CVE-2025-39688

MEDIUM

Linux Kernel - NFS Delegation State Lookup Bypass via SC_STATUS_FREEABLE Flag

Title source: llm
STIX 2.1

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: allow SC_STATUS_FREEABLE when searching via nfs4_lookup_stateid() The pynfs DELEG8 test fails when run against nfsd. It acquires a delegation and then lets the lease time out. It then tries to use the deleg stateid and expects to see NFS4ERR_DELEG_REVOKED, but it gets bad NFS4ERR_BAD_STATEID instead. When a delegation is revoked, it's initially marked with SC_STATUS_REVOKED, or SC_STATUS_ADMIN_REVOKED and later, it's marked with the SC_STATUS_FREEABLE flag, which denotes that it is waiting for s FREE_STATEID call. nfs4_lookup_stateid() accepts a statusmask that includes the status flags that a found stateid is allowed to have. Currently, that mask never includes SC_STATUS_FREEABLE, which means that revoked delegations are (almost) never found. Add SC_STATUS_FREEABLE to the always-allowed status flags, and remove it from nfsd4_delegreturn() since it's now always implied.

Scores

CVSS v3 5.5
EPSS 0.0024
EPSS Percentile 15.1%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Details

Status published
Products (17)
linux/Kernel 6.12.0 - 6.12.23linux
linux/Kernel 6.13.0 - 6.13.11linux
linux/Kernel 6.14.0 - 6.14.2linux
Linux/Linux < 6.12
Linux/Linux 6.11.6 - 6.12
Linux/Linux 6.12
Linux/Linux 6.12.23 - 6.12.*
Linux/Linux 6.13.11 - 6.13.*
Linux/Linux 6.14.2 - 6.14.*
Linux/Linux 6.15
... and 7 more
Published Apr 18, 2025
Tracked Since Feb 18, 2026