CVE-2025-39967

fbcon: fix integer overflow in fbcon_do_set_font

State: Published
Severity: 7.8 High
Published: Oct 15, 2025
Updated: Aug 5, 2026
Reserved: Apr 16, 2025

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.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	96e41fc29e8af5c5085fb8a79cab8d0d00bab86c to before 994bdc2d23c79087fbf7dcd9544454e8ebcef877Affected 39b3cffb8cf3111738ea993e2757ab382253d86a to before 9c8ec14075c5317edd6b242f1be8167aa1e4e333Affected 39b3cffb8cf3111738ea993e2757ab382253d86a to before b8a6e85328aeb9881531dbe89bcd2637a06c3c95Affected 39b3cffb8cf3111738ea993e2757ab382253d86a to before a6eb9f423b3db000aaedf83367b8539f6b72dcfcAffected 39b3cffb8cf3111738ea993e2757ab382253d86a to before adac90bb1aaf45ca66f9db8ac100be16750ace78Affected 39b3cffb8cf3111738ea993e2757ab382253d86a to before 4a4bac869560f943edbe3c2b032062f6673b13d3Affected 39b3cffb8cf3111738ea993e2757ab382253d86a to before c0c01f9aa08c8e10e10e8c9ebb5be01a4eff6eb7Affected 39b3cffb8cf3111738ea993e2757ab382253d86a to before 1a194e6c8e1ee745e914b0b7f50fa86c89ed13feAffected ae021a904ac82d9fc81c25329d3c465c5a7d5686Affected 451bffa366f2cc0e5314807cb847f31c0226efedAffected 2c455e9c5865861f5ce09c5f596909495ed7657cAffected 72f099805dbc907fbe8fa19bccdc31d3e2ee6e9eAffected 34cf1aff169dc6dedad8d79da7bf1b4de2773dbcAffected 5.4.62 to before 5.4.300Affected 4.4.235 to before 4.5Affected 4.9.235 to before 4.10Affected 4.14.196 to before 4.15Affected 4.19.143 to before 4.20Affected 5.8.6 to before 5.9Affected
LinuxLinux	5.9Affected before 5.9Not affected 5.4.300 through 5.4.Not affected 5.10.245 through 5.10.Not affected 5.15.194 through 5.15.Not affected 6.1.155 through 6.1.Not affected 6.6.109 through 6.6.Not affected 6.12.50 through 6.12.Not affected 6.16.10 through 6.16.*Not affected 6.17 and laterNot affected

Product

Versions

LinuxLinux

96e41fc29e8af5c5085fb8a79cab8d0d00bab86c to before 994bdc2d23c79087fbf7dcd9544454e8ebcef877Affected
39b3cffb8cf3111738ea993e2757ab382253d86a to before 9c8ec14075c5317edd6b242f1be8167aa1e4e333Affected
39b3cffb8cf3111738ea993e2757ab382253d86a to before b8a6e85328aeb9881531dbe89bcd2637a06c3c95Affected
39b3cffb8cf3111738ea993e2757ab382253d86a to before a6eb9f423b3db000aaedf83367b8539f6b72dcfcAffected
39b3cffb8cf3111738ea993e2757ab382253d86a to before adac90bb1aaf45ca66f9db8ac100be16750ace78Affected
39b3cffb8cf3111738ea993e2757ab382253d86a to before 4a4bac869560f943edbe3c2b032062f6673b13d3Affected
39b3cffb8cf3111738ea993e2757ab382253d86a to before c0c01f9aa08c8e10e10e8c9ebb5be01a4eff6eb7Affected
39b3cffb8cf3111738ea993e2757ab382253d86a to before 1a194e6c8e1ee745e914b0b7f50fa86c89ed13feAffected
ae021a904ac82d9fc81c25329d3c465c5a7d5686Affected
451bffa366f2cc0e5314807cb847f31c0226efedAffected
2c455e9c5865861f5ce09c5f596909495ed7657cAffected
72f099805dbc907fbe8fa19bccdc31d3e2ee6e9eAffected
34cf1aff169dc6dedad8d79da7bf1b4de2773dbcAffected
5.4.62 to before 5.4.300Affected
4.4.235 to before 4.5Affected
4.9.235 to before 4.10Affected
4.14.196 to before 4.15Affected
4.19.143 to before 4.20Affected
5.8.6 to before 5.9Affected

LinuxLinux

5.9Affected
before 5.9Not affected
5.4.300 through 5.4.*Not affected
5.10.245 through 5.10.*Not affected
5.15.194 through 5.15.*Not affected
6.1.155 through 6.1.*Not affected
6.6.109 through 6.6.*Not affected
6.12.50 through 6.12.*Not affected
6.16.10 through 6.16.*Not affected
6.17 and laterNot affected

References

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