Linux Distros Unpatched Vulnerability : CVE-2026-89666

medium Nessus Plugin ID 345122

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Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

- 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. (CVE-2026-89666)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

Plugin Details

Severity: Medium

ID: 345122

File Name: unpatched_CVE_2026_89666.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 9/12/2026

Updated: 9/12/2026

Supported Sensors: Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.61

CVSS v2

Risk Factor: Medium

Base Score: 5.2

Temporal Score: 4.4

Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:P/A:C

CVSS Score Source: CVE-2026-89666

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 5.1

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:U/RC:C

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:12.0, cpe:/o:debian:debian_linux:13.0, cpe:/o:debian:debian_linux:14.0, p-cpe:/a:debian:debian_linux:linux

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 9/11/2026

Reference Information

CVE: CVE-2026-89666

Detections

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