CVE-2025-39967
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-15

Last updated on: 2026-02-26

Assigner: kernel.org

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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Meta Information
Published
2025-10-15
Last Modified
2026-02-26
Generated
2026-05-06
AI Q&A
2025-10-15
EPSS Evaluated
2026-05-05
NVD
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
linux linux_kernel 5.9
linux linux_kernel 6.17
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-190 The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is an integer overflow in the Linux kernel's fbcon_do_set_font() function. It occurs when calculations for font size, based on user-controlled parameters, overflow during multiplication or addition. This causes the system to allocate less memory than needed, leading to buffer overflows when copying font data. The issue was fixed by adding explicit overflow checks to ensure safe size calculations before memory allocation.


How can this vulnerability impact me? :

The vulnerability can lead to buffer overflows in the Linux kernel when handling font data, which may cause system instability, crashes, or potentially allow an attacker to execute arbitrary code with kernel privileges if exploited.


What immediate steps should I take to mitigate this vulnerability?

Update the Linux kernel to a version that includes the fix for the integer overflow in fbcon_do_set_font(), which adds explicit overflow checking to prevent buffer overflows. Until then, avoid using untrusted user-controlled font parameters that could trigger the vulnerability.


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