{"id":"CVE-2026-64388","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb/client: fix chown/chgrp with SMB3 POSIX Extensions\n\nOwnership (chown) and group (chgrp) modifications were being ignored when\nmounting with SMB3 POSIX Extensions un…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb/client: fix chown/chgrp with SMB3 POSIX Extensions\n\nOwnership (chown) and group (chgrp) modifications were being ignored when\nmounting with SMB3 POSIX Extensions un…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 4.18, < 7.1.4"],"patched":["linux_kernel 7.1.4"],"published":"2026-07-25","updated":"2026-10-15","sourceUpdated":"2026-10-15T11:17:40.047","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-64388","references":[{"url":"https://git.kernel.org/stable/c/3eaec47518e126e6dcd1a48521d740278073f0ec","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/550cfb8a81181331d4d0f76ab75ee58a0bf41e3e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/760ef2c579c2609cf17fb1cd5392f64d42d43d33","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6825a45f6b8ef76b0ee32649ec3d6e39ca143a18"},{"url":"https://git.kernel.org/stable/c/27ead8c5418af6bfab711079fecb9414d78d4cae"}],"tags":["nvd","cve.org"],"epss":0.00133,"epssPercentile":0.02846,"ingestedAt":"2026-09-05T13:39:57.352Z","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:40:07.284651Z"},"slug":"CVE-2026-64388","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsmb/client: fix chown/chgrp with SMB3 POSIX Extensions\n\nOwnership (chown) and group (chgrp) modifications were being ignored when\nmounting with SMB3 POSIX Extensions unless CIFS_MOUNT_CIFS_ACL or\nCIFS_MOUNT_MODE_FROM_SID were also explicitly set.\n\nFix this by checking for posix_extensions in cifs_setattr_nounix() when\nupdating UID and GID, ensuring that id_mode_to_cifs_acl() is called to map\nand set the ownership/group information on the server.\n\n## Affected\n\n- `linux_kernel >= 4.18, < 7.1.4`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.1.4`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}