CVE intelligence

CVE-2026-89640

Vulnerability intelligence

Published Sep 11, 2026Sources checked Nov 3, 2026

7.1HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-89640 and is rated High severity with a CVSS score of 7.1. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.1%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-89640?

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

cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0

With len == 0 (clone to EOF), the effective length is computed as:

len = src_inode->i_size - off;

If off > i_size, this is a negative loff_t, corrupting the ByteCount in the FSCTL_DUPLICATE_EXTENTS_TO_FILE request and inverting the range in filemap_write_and_wait_range(). The existing off >= i_size check fires only after the ioctl has already been sent.

Snapshot i_size_read() once for both the bounds check and the length calculation, eliminating the TOCTOU and 32-bit torn-read risk. Reject off > src_size with -EINVAL.

Treat off == src_size as a no-op, consistent with __generic_remap_file_range_prep().

Source: NVD