Linux Distros Unpatched Vulnerability : CVE-2026-89722

high Nessus Plugin ID 345120

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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.

- PCI/sysfs: Fix out-of-bounds read in pci_write_legacy_io() pci_write_legacy_io() loads 4 bytes from the kernfs write buffer regardless of how many bytes userspace wrote: if (count != 1 && count != 2 && count != 4) return -EINVAL; return pci_legacy_write(bus, off, *(u32 *)buf, count); kernfs_fop_write_iter() allocates the buffer with kmalloc(len + 1), so a 1-byte write to the legacy_io sysfs file allocates 2 bytes and the unconditional u32 load reads up to 2 bytes past the end of the allocation, which KASAN reports as a slab-out-of-bounds read. Similarly, a 2-byte write overreads by 1 byte. Thus, read only the number of bytes requested using get_unaligned_le16() and get_unaligned_le32() for the 2 and 4 byte cases, interpreting the buffer as little-endian to match the byte ordering of PCI I/O port space. The PowerPC implementation previously compensated for the generic code's native-endian 32-bit load by shifting the value into place for the 1 and 2 byte cases. The shifts were only correct on big-endian kernels. On little-endian PowerPC (POWER8 and later), they extracted the wrong bytes, so a 1-byte write wrote an out- of-bounds byte instead of the requested value. On big-endian, the native load also caused out_le16() and out_le32() to reverse the user's bytes on the wire for 2 and 4 byte writes. The little-endian helpers resolve both issues, so the shifts are removed. No changes are needed for the Alpha platform. The legacy_io file is root-only and exists only on Alpha and PowerPC, the two architectures that define HAVE_PCI_LEGACY. (CVE-2026-89722)

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: High

ID: 345120

File Name: unpatched_CVE_2026_89722.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: Medium

Score: 4.9

Percentile: 58.23

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.9

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

CVSS Score Source: CVE-2026-89722

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 7.1

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-2026-89722

Detections

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