Description
In the Linux kernel, the following vulnerability has been resolved:
nfsd: reject out-of-range nseconds in NFSv3 SETATTR and create ops
A client can send an NFSv3 SETATTR, CREATE, MKDIR, SYMLINK or MKNOD
carrying an atime or mtime whose nseconds field is out of range. The
value is well-formed on the wire and decodes cleanly into a valid
uint32, but it is not a valid timespec64: tv_nsec must be less than
NSEC_PER_SEC.
Nothing in the setattr path clamps it. notify_change() runs the time
through timestamp_truncate(), which does not reduce tv_nsec below
NSEC_PER_SEC when the filesystem supports nanosecond granularity
(s_time_gran == 1), and the inode atime/mtime setters store it verbatim
(only ctime is normalized, via inode_set_ctime_to_ts()). The
un-normalized value then corrupts on-disk metadata: ext4's
ext4_encode_extra_time() shifts tv_nsec left by EXT4_EPOCH_BITS, which
overflows the 32-bit extra field and clobbers the seconds-epoch bits, so
the stored seconds (and thus the year) are wrong on read-back. XFS with
bigtime mis-stores the timestamp for the same reason.
Validate the client-supplied atime/mtime in the proc handlers and return
NFS3ERR_INVAL before anything is changed. RFC 1813 lists NFS3ERR_INVAL
for SETATTR and describes it as the error for a value the server 'can
not store ... in its own representation'; the client maps it to EINVAL.
Checking in the proc handlers, rather than in nfsd_setattr(), keeps the
rejection in front of object creation. The create operations create the
object before nfsd_create_setattr() runs, so a late failure would leave
the new object behind and turn a non-idempotent request into a namespace
change that reports failure. The check is therefore done up front, for
the create operations before the object is created.
tv_nsec is a long, so the comparison casts it to unsigned long (the same
width) rather than to u32, matching timespec64_valid(). A u32 cast would
truncate on 64-bit; the unsigned long cast also rejects a value that
became negative when an out-of-range u32 wire nseconds was assigned to a
32-bit long.
Only client-supplied times are checked: SET_TO_SERVER_TIME requests
carry no client value. The sattrguard3 ctime is deliberately left alone:
an out-of-range guard simply never matches the object's ctime and yields
NFS3ERR_NOT_SYNC via the existing guardtime comparison, which is the
protocol-correct outcome rather than rejecting the request.
nfsd: reject out-of-range nseconds in NFSv3 SETATTR and create ops
A client can send an NFSv3 SETATTR, CREATE, MKDIR, SYMLINK or MKNOD
carrying an atime or mtime whose nseconds field is out of range. The
value is well-formed on the wire and decodes cleanly into a valid
uint32, but it is not a valid timespec64: tv_nsec must be less than
NSEC_PER_SEC.
Nothing in the setattr path clamps it. notify_change() runs the time
through timestamp_truncate(), which does not reduce tv_nsec below
NSEC_PER_SEC when the filesystem supports nanosecond granularity
(s_time_gran == 1), and the inode atime/mtime setters store it verbatim
(only ctime is normalized, via inode_set_ctime_to_ts()). The
un-normalized value then corrupts on-disk metadata: ext4's
ext4_encode_extra_time() shifts tv_nsec left by EXT4_EPOCH_BITS, which
overflows the 32-bit extra field and clobbers the seconds-epoch bits, so
the stored seconds (and thus the year) are wrong on read-back. XFS with
bigtime mis-stores the timestamp for the same reason.
Validate the client-supplied atime/mtime in the proc handlers and return
NFS3ERR_INVAL before anything is changed. RFC 1813 lists NFS3ERR_INVAL
for SETATTR and describes it as the error for a value the server 'can
not store ... in its own representation'; the client maps it to EINVAL.
Checking in the proc handlers, rather than in nfsd_setattr(), keeps the
rejection in front of object creation. The create operations create the
object before nfsd_create_setattr() runs, so a late failure would leave
the new object behind and turn a non-idempotent request into a namespace
change that reports failure. The check is therefore done up front, for
the create operations before the object is created.
tv_nsec is a long, so the comparison casts it to unsigned long (the same
width) rather than to u32, matching timespec64_valid(). A u32 cast would
truncate on 64-bit; the unsigned long cast also rejects a value that
became negative when an out-of-range u32 wire nseconds was assigned to a
32-bit long.
Only client-supplied times are checked: SET_TO_SERVER_TIME requests
carry no client value. The sattrguard3 ctime is deliberately left alone:
an out-of-range guard simply never matches the object's ctime and yields
NFS3ERR_NOT_SYNC via the existing guardtime comparison, which is the
protocol-correct outcome rather than rejecting the request.
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data available yet.
Remediation
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Advisories
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References
History
Sat, 12 Sep 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Sat, 12 Sep 2026 09:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-190 CWE-20 |
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: reject out-of-range nseconds in NFSv3 SETATTR and create ops A client can send an NFSv3 SETATTR, CREATE, MKDIR, SYMLINK or MKNOD carrying an atime or mtime whose nseconds field is out of range. The value is well-formed on the wire and decodes cleanly into a valid uint32, but it is not a valid timespec64: tv_nsec must be less than NSEC_PER_SEC. Nothing in the setattr path clamps it. notify_change() runs the time through timestamp_truncate(), which does not reduce tv_nsec below NSEC_PER_SEC when the filesystem supports nanosecond granularity (s_time_gran == 1), and the inode atime/mtime setters store it verbatim (only ctime is normalized, via inode_set_ctime_to_ts()). The un-normalized value then corrupts on-disk metadata: ext4's ext4_encode_extra_time() shifts tv_nsec left by EXT4_EPOCH_BITS, which overflows the 32-bit extra field and clobbers the seconds-epoch bits, so the stored seconds (and thus the year) are wrong on read-back. XFS with bigtime mis-stores the timestamp for the same reason. Validate the client-supplied atime/mtime in the proc handlers and return NFS3ERR_INVAL before anything is changed. RFC 1813 lists NFS3ERR_INVAL for SETATTR and describes it as the error for a value the server 'can not store ... in its own representation'; the client maps it to EINVAL. Checking in the proc handlers, rather than in nfsd_setattr(), keeps the rejection in front of object creation. The create operations create the object before nfsd_create_setattr() runs, so a late failure would leave the new object behind and turn a non-idempotent request into a namespace change that reports failure. The check is therefore done up front, for the create operations before the object is created. tv_nsec is a long, so the comparison casts it to unsigned long (the same width) rather than to u32, matching timespec64_valid(). A u32 cast would truncate on 64-bit; the unsigned long cast also rejects a value that became negative when an out-of-range u32 wire nseconds was assigned to a 32-bit long. Only client-supplied times are checked: SET_TO_SERVER_TIME requests carry no client value. The sattrguard3 ctime is deliberately left alone: an out-of-range guard simply never matches the object's ctime and yields NFS3ERR_NOT_SYNC via the existing guardtime comparison, which is the protocol-correct outcome rather than rejecting the request. | |
| Title | nfsd: reject out-of-range nseconds in NFSv3 SETATTR and create ops | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-11T19:45:52.864Z
Reserved: 2026-09-11T19:38:34.745Z
Link: CVE-2026-89666
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-11T20:19:53.050
Modified: 2026-09-11T20:19:53.050
Link: CVE-2026-89666
Redhat
OpenCVE Enrichment
Updated: 2026-09-12T08:45:11Z