CVE-2025-38198: fbcon: Make sure modelist not set on unregistered console

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-04 · updated 2026-06-17
Weakness: CWE-129

Description

In the Linux kernel, the following vulnerability has been resolved: fbcon: Make sure modelist not set on unregistered console It looks like attempting to write to the "store_modes" sysfs node will run afoul of unregistered consoles: UBSAN: array-index-out-of-bounds in drivers/video/fbdev/core/fbcon.c:122:28 index -1 is out of range for type 'fb_info *[32]' ... fbcon_info_from_console+0x192/0x1a0 drivers/video/fbdev/core/fbcon.c:122 fbcon_new_modelist+0xbf/0x2d0 drivers/video/fbdev/core/fbcon.c:3048 fb_new_modelist+0x328/0x440 drivers/video/fbdev/core/fbmem.c:673 store_modes+0x1c9/0x3e0 drivers/video/fbdev/core/fbsysfs.c:113 dev_attr_store+0x55/0x80 drivers/base/core.c:2439 static struct fb_info *fbcon_registered_fb[FB_MAX]; ... static signed char con2fb_map[MAX_NR_CONSOLES]; ... static struct fb_info *fbcon_info_from_console(int console) ... return fbcon_registered_fb[con2fb_map[console]]; If con2fb_map contains a -1 things go wrong here. Instead, return NULL, as callers of fbcon_info_from_console() are trying to compare against existing "info" pointers, so error handling should kick in correctly.

Affected products

Debian Linux: 11.0
Linux kernel: before 6.1.142; from 6.2 before 6.6.95; from 6.7 before 6.12.35; from 6.13 before 6.15.4 — fixed in 6.1.142, 6.12.35, 6.15.4, 6.6.95

How to fix

Upgrade to a fixed version: Linux kernel 6.1.142, 6.12.35, 6.15.4, 6.6.95. Check the vendor advisory for mitigations.

References

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