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Back to active CVEs
High · CVSS 7.1CVE-2026-89640

cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0CVE-2026-89640

Answer in brief

CVE-2026-89640 records a High severity (CVSS 7.1) vulnerability in cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 11, 2026Updated Oct 19, 2026Source checked Oct 27, 2026First seen by HOL Sep 11, 2026Material review Oct 19, 2026
Upstream Advisory

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
Not reported
Source
CVE List V5
Source checked
Oct 27, 2026
References
6 linked sources
Open source record

Key facts

Risk
High · CVSS 7.1
Exploitation
Not marked as known exploited
Affected software
3 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 7.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Linux/Linuxgeneric>=04b38d601239b4d9be641b412cf4b7456a041c67 <b098f5e5858797827666e6cd73033f52fc39b5f6 || >=04b38d601239b4d9be641b412cf4b7456a041c67 <c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028 || >=04b38d601239b4d9be641b412cf4b7456a041c67 <b057ca17b656345d04669cb87f2aff9b31d873db || >=04b38d601239b4d9be641b412cf4b7456a041c67 <6c322f5cf7476ded7a9a20f7be72462065a03c68b098f5e5858797827666e6cd73033f52fc39b5f6, c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028, b057ca17b656345d04669cb87f2aff9b31d873db, 6c322f5cf7476ded7a9a20f7be72462065a03c68
Linux/Linuxgeneric4.5Not reported
Linux/Linuxgeneric>=04b38d601239b4d9be641b412cf4b7456a041c67 <f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4 || >=04b38d601239b4d9be641b412cf4b7456a041c67 <7f62817fe049b0f3652518c1ba72631ec1e0a322 || >=04b38d601239b4d9be641b412cf4b7456a041c67 <b098f5e5858797827666e6cd73033f52fc39b5f6 || >=04b38d601239b4d9be641b412cf4b7456a041c67 <c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028 || >=04b38d601239b4d9be641b412cf4b7456a041c67 <b057ca17b656345d04669cb87f2aff9b31d873db || >=04b38d601239b4d9be641b412cf4b7456a041c67 <6c322f5cf7476ded7a9a20f7be72462065a03c68f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4, 7f62817fe049b0f3652518c1ba72631ec1e0a322, b098f5e5858797827666e6cd73033f52fc39b5f6, c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028, b057ca17b656345d04669cb87f2aff9b31d873db, 6c322f5cf7476ded7a9a20f7be72462065a03c68

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux, Linux/Linux.
  2. 2Review the reported fix. Update Linux/Linux to b098f5e5858797827666e6cd73033f52fc39b5f6; Linux/Linux to f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Sep 11, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 19, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Sep 11, 2026

Sources and claim methodology

  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
Upstream source 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().

Quoted source text, attributed separately from HOL analysis.