7.8

CVE-2026-89793

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

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.
Daten sind bereitgestellt durch das CVE Programm von einer CVE Numbering Authority (CNA) (Unstrukturiert).
HerstellerLinux
≫
Produkt Linux
Default Statusunaffected
Version 71f28f3136aff5890cd56de78abc673f8393cad9
Version < be41733c24be58e2a1ef718c80fafdfb98a40d5e
Status affected
Version 71f28f3136aff5890cd56de78abc673f8393cad9
Version < 5befd06a72216869b607cf7724a4f16c6a2d3999
Status affected
Version 71f28f3136aff5890cd56de78abc673f8393cad9
Version < e373c1acdbcf88cec533ece9f589020adaed0a78
Status affected
Version 71f28f3136aff5890cd56de78abc673f8393cad9
Version < fa5e1bc673ca59722608af67b27e65dba0c97926
Status affected
Version 71f28f3136aff5890cd56de78abc673f8393cad9
Version < 6e2b571b0a54755b06e092501913e1dfefe75d6c
Status affected
HerstellerLinux
≫
Produkt Linux
Default Statusaffected
Version 6.0
Status affected
Version 0
Version < 6.0
Status unaffected
Version <= 6.6.*
Version 6.6.157
Status unaffected
Version <= 6.12.*
Version 6.12.110
Status unaffected
Version <= 6.18.*
Version 6.18.51
Status unaffected
Version <= 7.2.*
Version 7.2.5
Status unaffected
Version <= *
Version 7.3-rc2
Status unaffected
VulnDex Vulnerability Enrichment
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.21% 0.112
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
416baaa9-dc9f-4396-8d5f-8c081fb06d67 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Es wurden noch keine Informationen zu CWE veröffentlicht.
https://git.kernel.org/stable/c/be41733c24be58e2a1ef718c80fafdfb98a40d5e
https://git.kernel.org/stable/c/5befd06a72216869b607cf7724a4f16c6a2d3999
https://git.kernel.org/stable/c/e373c1acdbcf88cec533ece9f589020adaed0a78
https://git.kernel.org/stable/c/fa5e1bc673ca59722608af67b27e65dba0c97926
https://git.kernel.org/stable/c/6e2b571b0a54755b06e092501913e1dfefe75d6c