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Fencer Intel
high 7.8

CVE-2025-40323 json

fbcon: Set fb_display[i]->mode to NULL when the mode is released

published 11mo ago modified 25d ago also EUVD-2025-201622

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

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

fbcon: Set fb_display[i]->mode to NULL when the mode is released

Recently, we discovered the following issue through syzkaller:

BUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0 Read of size 4 at addr ff11000001b3c69c by task syz.xxx ... Call Trace: <TASK> dump_stack_lvl+0xab/0xe0 print_address_description.constprop.0+0x2c/0x390 print_report+0xb9/0x280 kasan_report+0xb8/0xf0 fb_mode_is_equal+0x285/0x2f0 fbcon_mode_deleted+0x129/0x180 fb_set_var+0xe7f/0x11d0 do_fb_ioctl+0x6a0/0x750 fb_ioctl+0xe0/0x140 __x64_sys_ioctl+0x193/0x210 do_syscall_64+0x5f/0x9c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Based on experimentation and analysis, during framebuffer unregistration, only the memory of fb_info->modelist is freed, without setting the corresponding fb_display[i]->mode to NULL for the freed modes. This leads to UAF issues during subsequent accesses. Here's an example of reproduction steps: 1. With /dev/fb0 already registered in the system, load a kernel module to register a new device /dev/fb1; 2. Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP); 3. Switch console from fb to VGA (to allow normal rmmod of the ko); 4. Unload the kernel module, at this point fb1's modelist is freed, leaving a wild pointer in fb_display[]; 5. Trigger the bug via system calls through fb0 attempting to delete a mode from fb0.

Add a check in do_unregister_framebuffer(): if the mode to be freed exists in fb_display[], set the corresponding mode pointer to NULL.

Patch / fix

  • Linux Linux 5.15.203, 6.1.159, 6.6.117, 6.12.58, 6.17.8, 6.18
  • linux Debian 12 6.1.159-1
  • linux Debian 13 6.12.63-1
  • linux Debian 14 6.17.8-1

debian advisories DEBIAN-CVE-2025-40323

  • linux Ubuntu 22.04 LTS 5.15.0-186.196
  • linux Ubuntu 24.04 LTS 6.8.0-106.106
  • linux Ubuntu 25.10 6.17.0-14.14
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1050.53
  • linux-aws Ubuntu 25.10 6.17.0-1007.7
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1052.55

ubuntu advisories UBUNTU-CVE-2025-40323

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt RHEL 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-kvm RHEL 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-core RHEL 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-modules RHEL 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-kvm RHEL 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-core RHEL 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-modules RHEL 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-modules-extra RHEL 8 4.18.0-553.169.1.rt7.510.el8_10

red hat advisories RHSA-2026:72467RHSA-2026:72468RHSA-2026:71700RHSA-2026:71602

  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-40.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-40.1
  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-default-base Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1.21.16
  • kernel-rt Linux Micro 6.2 6.12.0-160000.9.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.9.1

suse advisories SUSE-SU-2026:20845-1SUSE-SU-2026:20876-1SUSE-SU-2026:20477-1SUSE-SU-2026:20498-1SUSE-SU-2026:0473-1SUSE-SU-2026:20207-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.9.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.9.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.9.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.9.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.9.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.9.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.9.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.9.1

opensuse advisories openSUSE-SU-2026:20145-1

  • kernel-rt AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-core AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-modules AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-core AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-modules AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-modules-extra AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-modules-extra AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel AlmaLinux 8 4.18.0-553.169.1.el8_10

almalinux advisories ALSA-2026:72467ALSA-2026:72468ALSA-2026:71700ALSA-2026:71602

  • kernel-rt Rocky Linux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel Rocky Linux 8 4.18.0-553.169.1.el8_10
  • kernel Rocky Linux 10 6.12.0-211.60.1.el10_2
  • kernel Rocky Linux 9 5.14.0-687.52.1.el9_8

rocky linux advisories RLSA-2026:72467RLSA-2026:72468RLSA-2026:71602RLSA-2026:71700

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-40323 updated cvss 5.8

kernel: fbcon: Set fb_display[i]->mode to NULL when the mode is released

  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.52.1.el9_8, perf 5.14.0-687.52.1.el9_8, rtla 5.14.0-687.52.1.el9_8, python3-perf 5.14.0-687.52.1.el9_8, kernel-devel-matched 5.14.0-687.52.1.el9_8, kernel-64k-devel-matched 5.14.0-687.52.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.60.1.el10_2, perf 6.12.0-211.60.1.el10_2, rtla 6.12.0-211.60.1.el10_2, python3-perf 6.12.0-211.60.1.el10_2, kernel-devel-matched 6.12.0-211.60.1.el10_2, kernel-64k-devel-matched 6.12.0-211.60.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:71602
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.169.1.el8_10, kernel 4.18.0-553.169.1.el8_10, bpftool 4.18.0-553.169.1.el8_10, kernel-core 4.18.0-553.169.1.el8_10, kernel-tools 4.18.0-553.169.1.el8_10, python3-perf 4.18.0-553.169.1.el8_10, +15 more
    fixed: vendor fix RHSA-2026:72468
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.52.1.el9_8, kernel-64k 5.14.0-687.52.1.el9_8, kernel-core 5.14.0-687.52.1.el9_8, kernel-tools 5.14.0-687.52.1.el9_8, kernel-modules 5.14.0-687.52.1.el9_8, kernel-64k-core 5.14.0-687.52.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.60.1.el10_2, kernel-64k 6.12.0-211.60.1.el10_2, kernel-core 6.12.0-211.60.1.el10_2, kernel-tools 6.12.0-211.60.1.el10_2, kernel-modules 6.12.0-211.60.1.el10_2, kernel-64k-core 6.12.0-211.60.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:71602
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.52.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.52.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.52.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.52.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.52.1.el9_8
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.60.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.60.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.60.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.60.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.60.1.el10_2
    fixed: vendor fix RHSA-2026:71602
show 8 more
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.169.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.169.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.169.1.el8_10
    fixed: vendor fix RHSA-2026:72468
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-kvm 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-kvm 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-core 4.18.0-553.169.1.rt7.510.el8_10, +4 more
    fixed: vendor fix RHSA-2026:72467
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.52.1.el9_8, kernel-rt-64k 5.14.0-687.52.1.el9_8, kernel-rt-core 5.14.0-687.52.1.el9_8, kernel-rt-modules 5.14.0-687.52.1.el9_8, kernel-rt-64k-core 5.14.0-687.52.1.el9_8, kernel-rt-debug-core 5.14.0-687.52.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.60.1.el10_2, kernel-rt-64k 6.12.0-211.60.1.el10_2, kernel-rt-core 6.12.0-211.60.1.el10_2, kernel-rt-modules 6.12.0-211.60.1.el10_2, kernel-rt-64k-core 6.12.0-211.60.1.el10_2, kernel-rt-debug-core 6.12.0-211.60.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:71602
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.52.1.el9_8, kernel-rt-core 5.14.0-687.52.1.el9_8, kernel-rt-modules 5.14.0-687.52.1.el9_8, kernel-rt-debug-core 5.14.0-687.52.1.el9_8, kernel-rt-modules-core 5.14.0-687.52.1.el9_8, kernel-rt-debug-modules 5.14.0-687.52.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.60.1.el10_2, kernel-rt-core 6.12.0-211.60.1.el10_2, kernel-rt-modules 6.12.0-211.60.1.el10_2, kernel-rt-debug-core 6.12.0-211.60.1.el10_2, kernel-rt-modules-core 6.12.0-211.60.1.el10_2, kernel-rt-debug-modules 6.12.0-211.60.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:71602
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules-extra 4.18.0-553.169.1.rt7.510.el8_10, +2 more
    fixed: vendor fix RHSA-2026:72467
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
25d ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.