CVE-2026-89793 Linux Kernel - Broken Access Control

Linux kernel contains a broken access control vulnerability caused by failure to clear VM_MAYWRITE on read-only ublk char device mmap, letting unprivileged userspace daemons escalate write permissions on read-only mappings, exploit requires unprivileged daemon access.

CVSS base score 7.8 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Required
EPSS
0.17% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Broken Access Control
Impact
Broken Access Control
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
16 September 2026
Updated
15 October 2026

Vendor fix

Update to the Linux kernel version containing the fix for clearing VM_MAYWRITE on ublk char device mmap or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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