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

What is CVE-2025-21738?

CVE-2025-21738 is a high-severity memory corruption vulnerability in Linux kernel, published on 27 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Which versions are affected by CVE-2025-21738?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-21738?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2025-21738 being exploited?

There is no known exploitation of CVE-2025-21738 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-68973, BELL-CVE-2025-21738, DEBIAN-CVE-2025-21738, GHSA-f4r5-w3wm-c5g6, ROOT-OS-DEBIAN-11-CVE-2025-21738, ROOT-OS-UBUNTU-2204-CVE-2025-21738 and 3 more.