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Vulnerability record · CVE-2025-39967 · published 15 October 2025

CVE-2025-39967: Linux kernel integer overflow vulnerability

Linux · Linux Kernel

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.

7.8 CVSS 3.1 High EPSS 0.17% · top 94.3% CWE-190 · Integer overflow
7.8CVSS 3.1 base score
0.17%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References
30 Jul 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/1a194e6c8e1ee745e914b0b7f50fa86c89ed13fe Patch
https://git.kernel.org/stable/c/4a4bac869560f943edbe3c2b032062f6673b13d3 Patch
https://git.kernel.org/stable/c/994bdc2d23c79087fbf7dcd9544454e8ebcef877 Patch
https://git.kernel.org/stable/c/9c8ec14075c5317edd6b242f1be8167aa1e4e333 Patch
https://git.kernel.org/stable/c/a6eb9f423b3db000aaedf83367b8539f6b72dcfc Patch
https://git.kernel.org/stable/c/adac90bb1aaf45ca66f9db8ac100be16750ace78 Patch
https://git.kernel.org/stable/c/b8a6e85328aeb9881531dbe89bcd2637a06c3c95 Patch
https://git.kernel.org/stable/c/c0c01f9aa08c8e10e10e8c9ebb5be01a4eff6eb7 Patch

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Source: NIST National Vulnerability Database (record CVE-2025-39967), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.