Integer overflow in Linux

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.

Vulnerability class: Integer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.002 (5.7th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 6th percentile — 5.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-39967: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

  • Linux — versions 6.12.50, 96e41fc29e8af5c5085fb8a79cab8d0d00bab86c, 5.4.62
  • Linux Kernel — versions 5.9, 6.17

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-39967?
CVE-2025-39967 is a high-severity vulnerability in Linux, classified under Integer Overflow or Wraparound. CVSS score: 7.8/10. Published 2025-10-15.
How severe is CVE-2025-39967?
High severity. CVSS v3 base score is 7.8 out of 10.