7.8

CVE-2026-64388: linux Incorrect Calculation

CVSS: 7.8v3.1HighModified
AliasesUBUNTU-CVE-2026-64388DEBIAN-CVE-2026-64388CGA-25rh-9jrg-9jr8
Published 25-07-2026Last modified 21-10-2026
Open JSON

Vulnerability summary

CVE-2026-64388 is a high (CVSS 7.8) Incorrect Calculation vulnerability in linux. EPSS estimates a 0.13% chance of exploitation in the next 30 days, higher than 2.1% of scored vulnerabilities.

Overall risk
31/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.13%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 25 · Related 25
OPENSUSE-SU-2026:11476-1OPENSUSE-SU-2026:22091-1SUSE-SU-2026:23477-1SUSE-SU-2026:23481-1SUSE-SU-2026:23528-1SUSE-SU-2026:23529-1

Timeline

  1. 25-07-2026
    PublishedVulnerability first disclosed.
  2. 21-10-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: smb/client: fix chown/chgrp with SMB3 POSIX Extensions Ownership (chown) and group (chgrp) modifications were being ignored when mounting with SMB3 POSIX Extensions unless CIFS_MOUNT_CIFS_ACL or CIFS_MOUNT_MODE_FROM_SID were also explicitly set. Fix this by checking for posix_extensions in cifs_setattr_nounix() when updating UID and GID, ensuring that id_mode_to_cifs_acl() is called to map and set the ownership/group information on the server.

CVSS metrics

6 scores · 5 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

+0.01 pp

From 0.12% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.13%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu155 products
  • linuxAll versions (No fix recorded) | < 7.0.0-31.31
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 7.0.0-1012.12
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Chainguard44 products
  • hyperv-daemons-6.18All versions (No fix recorded)
  • linux-aws-6.18All versions (No fix recorded)
  • linux-aws-6.18-boot-installedAll versions (No fix recorded)
  • linux-aws-6.18-bootcAll versions (No fix recorded)
  • linux-aws-6.18-bootc-boot-installedAll versions (No fix recorded)
Debian1 product
  • linuxAll versions (No fix recorded) | < 7.1.4-1

3 vendors · 200 products · Showing 200 of 212. Use Open JSON for the complete list.

References

24 links
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