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CVE-2026-89640

HIGHCVSS 7.1/10EPSS 0.13%

Last modified

CVE-2026-89640 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.13% chance of exploitation in the next 30 days.

Description

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().

Metrics

CVSS 3.1
7.1/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

EPSS Probability
0.13%

2.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 04b38d601239b4d9be641b412cf4b7456a041c67, < f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4; >= 04b38d601239b4d9be641b412cf4b7456a041c67, < 7f62817fe049b0f3652518c1ba72631ec1e0a322; >= 04b38d601239b4d9be641b412cf4b7456a041c67, < b098f5e5858797827666e6cd73033f52fc39b5f6; >= 04b38d601239b4d9be641b412cf4b7456a041c67, < c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028; >= 04b38d601239b4d9be641b412cf4b7456a041c67, < b057ca17b656345d04669cb87f2aff9b31d873db; >= 04b38d601239b4d9be641b412cf4b7456a041c67, < 6c322f5cf7476ded7a9a20f7be72462065a03c68
LinuxLinux4.5

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

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().
How severe is CVE-2026-89640?
CVE-2026-89640 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.
How do I fix CVE-2026-89640?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST