CVE-2025-40323

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2025-12-08. the CNA's CVSS baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:linux, epss, ghsa
Trending — 5 sources updated this week
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

A fix is available — apply it.

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: 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:

  • With /dev/fb0 already registered in the system, load a kernel module
to register a new device /dev/fb1;
  • Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP);
  • Switch console from fb to VGA (to allow normal rmmod of the ko);
  • Unload the kernel module, at this point fb1's modelist is freed, leaving
a wild pointer in fb_display[];
  • 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.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity78% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
4%
KEV
Not listed

Published

December 8, 2025

Last Modified

August 5, 2026

Advisory Details (6)

Auto-updated Jul 30, 2026
No patch confirmed yet.
generic

fbcon: Set fb_display[i]->mode to NULL when the mode is released - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/de89d19f4f30d9a8de87b9d08c1bd35cb70576d8
generic

fbcon: Set fb_display[i]->mode to NULL when the mode is released - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c079d42f70109512eee49123a843be91d8fa133f
generic

fbcon: Set fb_display[i]->mode to NULL when the mode is released - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a1f3058930745d2b938b6b4f5bd9630dc74b26b7
generic

fbcon: Set fb_display[i]->mode to NULL when the mode is released - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb
generic

fbcon: Set fb_display[i]->mode to NULL when the mode is released - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/468f78276a37f4c6499385a4ce28f4f57be6655d
generic

fbcon: Set fb_display[i]->mode to NULL when the mode is released - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/39c2c1a2773aaf73e56906e5ef670114eb2d354f

Vendor Advisories for CVE-2025-40323(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(26)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-24.04-edge (6.17.0-14.14) @ questing2026-07-30ubuntu
ubuntulinux-tools-gcp-64k-6.17 (6.17.0-1007.7) @ questing2026-07-30ubuntu
ubuntulinux-tools-oracle-64k-6.17 (6.17.0-1007.7) @ questing2026-07-30ubuntu
ubuntulinux-tools-oem-6.17 (6.17.0-1011.11) @ noble2026-07-30ubuntu
ubuntulinux-tools-azure-6.17 (6.17.0-1008.8) @ questing2026-07-30ubuntu
ubuntulinux-virtual-6.8 (6.8.0-106.106) @ noble2026-07-30ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1049.52.1) @ noble2026-07-30ubuntu
ubuntulinux-tools-gcp-fips-6.8 (6.8.0-1052.55+fips1) @ noble2026-07-30ubuntu
ubuntulinux-tools-realtime-6.8.1 (6.8.1-1045.46) @ noble2026-07-30ubuntu
ubuntulinux-tools-aws-edge (6.8.0-1050.53~22.04.1) @ jammy2026-07-30ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1051.57) @ noble2026-07-30ubuntu
ubuntulinux-tools-azure-edge (6.8.0-1051.57~22.04.1) @ jammy2026-07-30ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2040.41) @ noble2026-07-30ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1052.58+fips1) @ noble2026-07-30ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1029.30) @ noble2026-07-30ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.15.0-1075 (5.15.0-1075.79) @ jammy2026-07-30ubuntu
ubuntulinux-tools-nvidia-lowlatency-5.15 (5.15.0.1107.107) @ jammy2026-07-30ubuntu
ubuntulinux-tools-nvidia-tegra-rt-5.15 (5.15.0.1064.66~20.04.1) @ focal2026-07-30ubuntu
ubuntulinux-tools-nvidia-tegra-rt-5.15 (5.15.0.1064.64) @ jammy2026-07-30ubuntu
ubuntulinux-tools-ibm-edge (5.15.0.1106.110~20.04.1) @ focal2026-07-30ubuntu
ubuntulinux-tools-oracle-lts-22.04 (5.15.0.1109.105) @ jammy2026-07-30ubuntu
ubuntulinux-tools-azure-fde-lts-22.04 (5.15.0.1117.126) @ jammy2026-07-30ubuntu
ubuntulinux-tools-oracle-edge (5.15.0.1109.115~20.04.1) @ focal2026-07-30ubuntu
ubuntulinux-tools-azure-fips-5.15 (5.15.0.1117.102) @ jammy2026-07-30ubuntu
linuxKernel @ 5.15.203—osv
linuxKernel @ 6.1.159—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

All Vendor Advisories

(25)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 13× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 139 total refreshes for this CVE.

  1. 2026-08-05 12:50 UTCEG score recompute
  2. 2026-08-05 12:50 UTCVendor advisory
  3. 2026-08-05 12:50 UTCGHSA enrichment
  4. 2026-08-04 15:09 UTCEPSS rescore
  5. 2026-08-04 10:37 UTCEPSS rescore
  6. 2026-08-03 10:35 UTCEPSS rescore
  7. 2026-08-02 02:26 UTCEPSS rescore
  8. 2026-08-01 04:15 UTCEPSS rescore
  9. 2026-07-30 16:27 UTCEPSS rescore
  10. 2026-07-30 06:24 UTCEG score recompute▲ 7.80
  11. 2026-07-30 06:24 UTCVendor advisory
  12. 2026-07-30 06:24 UTCGHSA enrichment
  13. 2026-07-30 06:18 UTCMITRE cvelistV5CVSS v3 → 7.8 · severity → HIGH
  14. 2026-07-30 01:29 UTCEPSS rescore
  15. 2026-07-28 15:35 UTCEPSS rescore
  16. 2026-07-27 06:09 UTCOSV refresh
  17. 2026-07-26 14:54 UTCEPSS rescore
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  21. 2026-07-23 02:55 UTCEG score recompute
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  24. 2026-07-21 15:24 UTCEPSS rescore
  25. 2026-07-20 17:07 UTCEPSS rescore
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  1. 2026-07-19 14:30 UTCEPSS rescore
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  17. 2026-07-10 00:45 UTCOSV refresh
  18. 2026-07-09 19:09 UTCEPSS rescore
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  20. 2026-07-07 13:45 UTCEPSS rescore
  21. 2026-07-06 16:27 UTCEPSS rescore
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  46. 2026-06-21 14:56 UTCEPSS rescore
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  48. 2026-06-21 11:31 UTCOSV refresh
  49. 2026-06-21 01:59 UTCEPSS rescore
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  74. 2026-06-02 03:09 UTCOSV refresh
  75. 2026-06-01 13:51 UTCEPSS rescore

Related CVEs(same product + same vendor)

Frequently asked(5)

What is CVE-2025-40323?
CVE-2025-40323 is a high vulnerability published on December 8, 2025. 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 fbmodeis_equal+0x285/0x2f0 Read of size 4 at addr ff11000001b3c69c…
When was CVE-2025-40323 disclosed?
CVE-2025-40323 was first published in the National Vulnerability Database on December 8, 2025, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-40323 actively exploited?
CVE-2025-40323 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 96.5% of all scored CVEs.
What is the CVSS score of CVE-2025-40323?
CVE-2025-40323 has a CVSS v4.0 base score of 7.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2025-40323?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-40323, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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