CVE-2026-89793 Affecting kernel-uek-modules-usb package, versions <0:6.12.0-207.111.5.1.el10uek


Severity

Recommended
high

Based on Oracle Linux security rating.

Threat Intelligence

EPSS
0.17% (6th percentile)

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  • Snyk IDSNYK-ORACLE10-KERNELUEKMODULESUSB-20583112
  • published8 Oct 2026
  • disclosed16 Sept 2026

Introduced: 16 Sep 2026

CVE-2026-89793  (opens in a new tab)

How to fix?

Upgrade Oracle:10 kernel-uek-modules-usb to version 0:6.12.0-207.111.5.1.el10uek or higher.
This issue was patched in ELSA-2026-500374.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-uek-modules-usb package and not the kernel-uek-modules-usb package as distributed by Oracle. See How to fix? for Oracle:10 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

ublk: clear VM_MAYWRITE on read-only ublk char device mmap

ublk_ch_mmap() rejects mmap requests with VM_WRITE set, but never clears VM_MAYWRITE on the resulting read-only mapping. This allows a userspace daemon to mmap the per-queue command buffer PROT_READ, then upgrade it to PROT_WRITE via mprotect(), since VM_MAYWRITE was never cleared.

The command buffer holds struct ublksrv_io_desc entries that are kernel-written ABI; a writable mapping lets an unprivileged daemon process corrupt fields such as addr, op_flags, nr_sectors, and start_sector.

Same bug class as the drm/panthor and drm/vc4 VM_MAYWRITE fixes, and the 2026-08-13 ptp/vmclock fix (a5edadbae57e).

Verified via mprotect() PoC: before the fix, a PROT_READ mapping can be upgraded to PROT_READ|PROT_WRITE and a write into the command buffer corrupts io_desc fields (confirmed under KASAN). After the fix, mprotect() returns -EACCES.

CVSS Base Scores

version 3.1