Bug 2419870 (CVE-2025-40304) - CVE-2025-40304 kernel: Linux kernel: Out-of-bounds write in fbdev can lead to privilege escalation, information disclosure, or denial of service.
Summary: CVE-2025-40304 kernel: Linux kernel: Out-of-bounds write in fbdev can lead to...
Keywords:
Status: NEW
Alias: CVE-2025-40304
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-12-08 07:04 UTC by OSIDB Bzimport
Modified: 2026-02-04 07:08 UTC (History)
0 users

Fixed In Version:
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System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:1727 0 None None None 2026-02-02 15:25:23 UTC

Description OSIDB Bzimport 2025-12-08 07:04:51 UTC
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.

Comment 4 errata-xmlrpc 2026-02-02 15:25:22 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:1727 https://access.redhat.com/errata/RHSA-2026:1727


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