CVE-2025-40304
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-08

Last updated on: 2025-12-08

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds Add bounds checking to prevent writes past framebuffer boundaries when rendering text near screen edges. Return early if the Y position is off-screen and clip image height to screen boundary. Break from the rendering loop if the X position is off-screen. When clipping image width to fit the screen, update the character count to match the clipped width to prevent buffer size mismatches. Without the character count update, bit_putcs_aligned and bit_putcs_unaligned receive mismatched parameters where the buffer is allocated for the clipped width but cnt reflects the original larger count, causing out-of-bounds writes.
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Meta Information
Published
2025-12-08
Last Modified
2025-12-08
Generated
2026-05-07
AI Q&A
2025-12-08
EPSS Evaluated
2026-05-05
NVD
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in the Linux kernel's framebuffer device (fbdev) involves a lack of proper bounds checking in the bit_putcs function. Without these checks, when rendering text near the edges of the screen, the code can write past the allocated framebuffer boundaries, causing out-of-bounds memory writes. The fix adds bounds checking to prevent writes beyond the screen edges by returning early if the Y position is off-screen, clipping the image height to the screen boundary, breaking the rendering loop if the X position is off-screen, and updating the character count to match the clipped width to avoid buffer size mismatches.


How can this vulnerability impact me? :

This vulnerability can lead to out-of-bounds memory writes when rendering text near screen edges in the Linux framebuffer. Such memory corruption can cause system instability, crashes, or potentially be exploited to execute arbitrary code or escalate privileges, depending on the context and attacker capabilities.


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