CVE-2025-40304

fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds

HIGH
7.8
CVSS Score
Published: December 8, 2025 at 12:46 AM UTC
Updated: October 14, 2026 at 10:10 PM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
HIGH7.8
Exploit prediction
EPSS 0.1%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Vendor states this is fixed in 15ba9acafb0517f8359ca30002c189a68ddbb939 (fixed)
Vendor states this is fixed in 1943b69e87b0ab35032d47de0a7fca9a3d1d6fc1 (fixed)
Vendor states this is fixed in 2d1359e11674ed4274934eac8a71877ae5ae7bbb (fixed)
Vendor states this is fixed in 3637d34b35b287ab830e66048841ace404382b67 (fixed)
Vendor states this is fixed in 86df8ade88d290725554cefd03101ecd0fbd3752 (fixed)
Vendor states this is fixed in 996bfaa7372d6718b6d860bdf78f6618e850c702 (fixed)
Vendor states this is fixed in ebc0730b490c7f27340b1222e01dd106e820320d (fixed)
Vendor states this is fixed in f0982400648a3e00580253e0c48e991f34d2684c (fixed)
Vendor states this is fixed in 2.6.12 (unaffected)
Vendor states this is fixed in 5.10.247 (unaffected)
Vendor states this is fixed in 5.15.197 (unaffected)
Vendor states this is fixed in 5.4.302 (unaffected)
Vendor states this is fixed in 6.1.159 (unaffected)
Vendor states this is fixed in 6.12.58 (unaffected)
Vendor states this is fixed in 6.17.8 (unaffected)
Vendor states this is fixed in 6.18 (unaffected)
Vendor states this is fixed in 6.6.117 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGHLinux
Vector?

Quick Info

StatusDEFERRED

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