CVE-2025-39967

High

Description

In the Linux kernel, the following vulnerability has been resolved: fbcon: fix integer overflow in fbcon_do_set_font Fix integer overflow vulnerabilities in fbcon_do_set_font() where font size calculations could overflow when handling user-controlled font parameters. The vulnerabilities occur when: 1. CALC_FONTSZ(h, pitch, charcount) performs h * pith * charcount multiplication with user-controlled values that can overflow. 2. FONT_EXTRA_WORDS * sizeof(int) + size addition can also overflow 3. This results in smaller allocations than expected, leading to buffer overflows during font data copying. Add explicit overflow checking using check_mul_overflow() and check_add_overflow() kernel helpers to safety validate all size calculations before allocation.

SeverityHigh
CVSS7.8
Exploit probability—
ProductLinux Kernel
PublishedOct 15, 2025
First seenOct 15, 2025

How to fix

Update
  • linux linux_kernel4.5, 4.10, 4.15, 4.20, 5.4.300, 5.9, 5.10.245, 5.15.194, 6.1.155, 6.6.109, 6.12.50, 6.16.10 or later

Affected products

ProductAffected versionsFixed in
linux linux_kernel4.4.235 ≤ v < 4.5, 4.9.235 ≤ v < 4.10, 4.14.196 ≤ v < 4.15, 4.19.143 ≤ v < 4.20, 5.4.62 ≤ v < 5.4.300, 5.8.6 ≤ v < 5.9, 5.9.1 ≤ v < 5.10.245, 5.11 ≤ v < 5.15.194, 5.16 ≤ v < 6.1.155, 6.2 ≤ v < 6.6.109, 6.7 ≤ v < 6.12.50, 6.13 ≤ v < 6.16.10, 5.9, 6.174.5, 4.10, 4.15, 4.20, 5.4.300, 5.9, 5.10.245, 5.15.194, 6.1.155, 6.6.109, 6.12.50, 6.16.10

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CVE-2025-39967 · Linux Kernel · Dark Radar