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CVE-2025-40323· NVD / CVE Program· CNA Linux

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

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.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Dec 7, 2025
Updated
Aug 5, 2026
EPSS
0.1% · 3th percentile
CWE
—
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Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 39c2c1a2773aaf73e56906e5ef670114eb2d354faffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 4ac18f0e6a6d599ca751c4cd98e522afc8e3d4ebaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 468f78276a37f4c6499385a4ce28f4f57be6655daffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before c079d42f70109512eee49123a843be91d8fa133faffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before de89d19f4f30d9a8de87b9d08c1bd35cb70576d8affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before a1f3058930745d2b938b6b4f5bd9630dc74b26b7affected · git
    • before 2.6.12not affected · semver
    • 5.15.203 and later · up to and including 5.15.*not affected · semver
    • 6.1.159 and later · up to and including 6.1.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8bpftoolbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernelbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-abi-stablelistsbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-corebefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-cross-headersbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-debugbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-debug-corebefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-debug-develbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-debug-modulesbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-debug-modules-extrabefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-develbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-docbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-headersbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-modulesbefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-modules-extrabefore 4.18.0-553.169.1.el8_104.18.0-553.169.1.el8_10
AlmaLinux:8kernel-rtbefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10
AlmaLinux:8kernel-rt-corebefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10
AlmaLinux:8kernel-rt-debugbefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10
AlmaLinux:8kernel-rt-debug-corebefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10
AlmaLinux:8kernel-rt-debug-develbefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10
AlmaLinux:8kernel-rt-debug-modulesbefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10
AlmaLinux:8kernel-rt-debug-modules-extrabefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10
AlmaLinux:8kernel-rt-develbefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10
AlmaLinux:8kernel-rt-modulesbefore 4.18.0-553.169.1.rt7.510.el8_104.18.0-553.169.1.rt7.510.el8_10

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

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Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux39c2c1a2773aaf73e56906e5ef670114eb2d354fVendor (CNA)
Linux Linux468f78276a37f4c6499385a4ce28f4f57be6655dVendor (CNA)
Linux Linux4ac18f0e6a6d599ca751c4cd98e522afc8e3d4ebVendor (CNA)
Linux Linuxa1f3058930745d2b938b6b4f5bd9630dc74b26b7Vendor (CNA)
Linux Linuxc079d42f70109512eee49123a843be91d8fa133fVendor (CNA)
Linux Linuxde89d19f4f30d9a8de87b9d08c1bd35cb70576d8Vendor (CNA)
almalinux:kernel5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-687.52.1.el9_8 · AlmaLinux:9Package registry (OSV)
debian:linux6.1.159-1 · Debian:12Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel-matched0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debuginfo0:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debuginfo-common-aarch640:6.12.0-211.60.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)

+2

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

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Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records