CVE-2025-40304: 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 ...

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.

Metrics

EPSS Probability

0.17%

6.0th percentile

Probability of exploitation in the next 30 days. Learn more

References

Timeline

Published: Dec 8, 2025
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2025-40304?

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.

How severe is CVE-2025-40304?

Severity scoring for CVE-2025-40304 is pending analysis. The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2025-40304?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.