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Review reviewHigh

CVE-2025-40323

Linux

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...

CVSS
7.8
EPSS
0.14%
3.55% percentile
CISA KEV
Not listed
Published
2025.12.08
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.14%
Technical severityCVSS 7.8

Vulnerability overview

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...

Affected product and versions

Product
Linux
Affected versions
>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 39c2c1a2773aaf73e56906e5ef670114eb2d354f, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 468f78276a37f4c6499385a4ce28f4f57be6655d, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c079d42f70109512eee49123a843be91d8fa133f, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < de89d19f4f30d9a8de87b9d08c1bd35cb70576d8, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a1f3058930745d2b938b6b4f5bd9630dc74b26b7, >= 2.6.12
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
Not available
CVE-2025-40323 — Linux | SECUFOCUS NOW