CVE-2025-39967: linux kernel Integer Overflow — Fix

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.

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CVSS v3.1 Score

7.8

HIGH

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

Weakness Type (CWE)

CWE-190 Integer Overflow

Affected Products

Vendor	Product	Versions
linux	linux_kernel	4.4.235 — 4.5
linux	linux_kernel	4.9.235 — 4.10
linux	linux_kernel	4.14.196 — 4.15
linux	linux_kernel	4.19.143 — 4.20
linux	linux_kernel	5.4.62 — 5.4.300
linux	linux_kernel	5.8.6 — 5.9
linux	linux_kernel	5.9.1 — 5.10.245
linux	linux_kernel	5.11 — 5.15.194
linux	linux_kernel	5.16 — 6.1.155
linux	linux_kernel	6.2 — 6.6.109
linux	linux_kernel	6.7 — 6.12.50
linux	linux_kernel	6.13 — 6.16.10
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

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

Frequently Asked Questions

What is CVE-2025-39967? +

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. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-39967? +

CVE-2025-39967 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-39967? +

CVE-2025-39967 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-39967? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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