7.1

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

Received
AliasesUBUNTU-CVE-2026-89640DEBIAN-CVE-2026-89640
Published 11-09-2026Last modified 30-10-2026

Vulnerability summary

CVE-2026-89640 is a high (CVSS 7.1) vulnerability in linux. EPSS estimates a 0.13% chance of exploitation in the next 30 days, higher than 2.3% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 7.1, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
7.1/10
010
High · v3.1 (CVE.org)
EPSS score
0.13%
0%100%
Low · -0.04 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 8 · Related 6
MGASA-2026-0506MGASA-2026-0542OPENSUSE-SU-2026:11880-1OPENSUSE-SU-2026:22167-1SUSE-SU-2026:24386-1SUSE-SU-2026:24422-1

Timeline

  1. 11-09-2026
    PublishedVulnerability first disclosed.
  2. 30-10-2026
    Last modifiedVulnerability information updated.

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().

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.13%

Chance of exploitation in the next 30 days

Percentile

2%

Versus all other CVEs

30-day change

Decrease -0.04 pp

From 0.17% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu168 products
  • linuxAll versions (No fix recorded)
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded)
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Debian2 products
  • linuxAll versions (No fix recorded) | < 6.1.190-1 | < 6.12.111-1 | < 7.2.6-1
  • linux-6.12< 6.12.111-1~deb12u1
Linux1 product
  • linux≥ 04b38d601239b4d9be641b412cf4b7456a041c67, < 2c6eede83b3de1268db92c7e49741761c954aa26 | ≥ 04b38d601239b4d9be641b412cf4b7456a041c67, < ce813e5eebf46851e872ce59bdc34dc5dd4e29a4 | ≥ 04b38d601239b4d9be641b412cf4b7456a041c67, < f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4 | ≥ 04b38d601239b4d9be641b412cf4b7456a041c67, < 7f62817fe049b0f3652518c1ba72631ec1e0a322 | ≥ 04b38d601239b4d9be641b412cf4b7456a041c67, < b098f5e5858797827666e6cd73033f52fc39b5f6 | ≥ 04b38d601239b4d9be641b412cf4b7456a041c67, < c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028 | ≥ 04b38d601239b4d9be641b412cf4b7456a041c67, < b057ca17b656345d04669cb87f2aff9b31d873db | ≥ 04b38d601239b4d9be641b412cf4b7456a041c67, < 6c322f5cf7476ded7a9a20f7be72462065a03c68 | 4.5

3 vendors · 171 products

References

13 links
Show all 13 references