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CVE-2026-89586

ata: libata-scsi: fix DSM TRIM for sector sizes larger than 2048 bytes

8.2 EPSS 0.6% AV:N

Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem drivers/ata. Debian urgency: not yet assigned.

What to do, per Debian release

Debian's own status for CVE-2026-89586 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source

Release	Status	Version	What this means
Debian 12bookworm	fixedDLA-4841-1 · 2026-10-17 · text	6.1.190-1	Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts.
Debian 13trixie	fixedDSA-6528-1 · 2026-09-29 · text	6.12.111-1	Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts.
Debian 14forky	fixed	7.2.6-1	Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts.
Debian unstablesid	fixed	7.2.6-1	Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts.
Debian 12bookworm · linux-6.12	fixedDLA-4817-1 · 2026-10-04 · text	6.12.111-1~deb12u1	Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts.

The vulnerability

What the bug is

ata_scsi_write_same_xlat() translates a SCSI WRITE SAME command with the UNMAP bit set into an ATA DATA SET MANAGEMENT TRIM command. The TRIM descriptor is built by ata_format_dsm_trim_descr() into the 2048-byte ata_scsi_rbuf staging buffer, and the number of bytes copied is compared against the logical sector size by the caller: size = ata_format_dsm_trim_descr(scmd, trmax, block, n_block); if (size != len) /* len == sdp->sector_size */ goto invalid_param_len; ata_format_dsm_trim_descr() clamps the copy length to ATA_SCSI_RBUF_SIZE (2048). On a device whose logical sector size exceeds that (e.g. a 4Kn device, where sector_size == 4096) the function can never return more than 2048, while the caller expects it to return sector_size. The comparison therefore always fails, so every TRIM is rejected with "Parameter list length error" and WARN_ON() splats on each attempt. TRIM / discard is thus completely broken on such devices. The descriptor was incorrectly sized from the logical sector size. A DSM TRIM payload is a list of 512-byte pages, each holding up to ATA_MAX_TRIM_RNUM (64) LBA Range Entries, and is independent of the logical sector size. The Block Limits VPD page already advertises a single such page as the maximum WRITE SAME length (65535 * ATA_MAX_TRIM_RNUM logical blocks), so the block layer never sends a request that needs more than one page. Emit exactly one 512-byte page, independent of the logical sector size, and transfer only that page (COUNT == 1). For a 512-byte-sector device this is unchanged; devices with larger logical sectors now work instead of failing every TRIM.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

drivers/ata/libata-scsi.c

What this is: LIBATA SUBSYSTEM (Serial and Parallel ATA drivers)MAINTAINERS section matched on drivers/ata/ · linux-ide@vger.kernel.org · Maintained
Kernel module: libata

Check it on the machine

grep -w CONFIG_ATA /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

lsmod | grep -w libata

Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.

Show whether Debian builds this, per release

Debian builds this code. Every release below compiles the affected file into the kernels it ships.

bookworm, trixie, forky, sid, bookworm · linux-6.12b

b: built in on some flavours, a module on others

Build switch: CONFIG_ATA

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Debian tracker CVE record NVD kernel CNA record

Signals

Published: 2026-09-11 (37 days ago)source
CVSS: 8.2 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:Hsource recompute it
Attack vector: network (AV:N)source
EPSS: 0.61%, higher than 48.4% of all CVEssource
CISA KEV: not listedthe KEV catalogue
Debian urgency: not yet assignedsource
Subsystem: drivers/ata

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
4.9	5.10.270	07975b8daa3b
4.9	5.15.221	b7b5ab2df325
4.9	6.1.188	07baa310ea32
4.9	6.6.157	977554ed91b5
4.9	6.12.109	04e2befe2579
4.9	6.18.50	c2e3dccd6870
4.9	7.2.4	4a4268a0b0a5
4.9	7.3	79cce911e623

Debian advisories

Advisory	Date	Shipped to	Debian
DLA-4841-1	2026-10-17	bookworm 6.1.190-1	tracker
DLA-4817-1	2026-10-04	bookworm 6.12.111-1~deb12u1	tracker
DSA-6528-1	2026-09-29	trixie 6.12.111-1	tracker

Why the CNA scored it this way

Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source

AV:NAttack vector, network: SATA/AHCI volumes commonly back NAS/SAN LUNs. Remote iSCSI UNMAP (target_core iblock_execute_unmap()/blkdev_issue_discard()), NFSv4.2 DEALLOCATE (nfsd4_deallocate), and ksmbd FSCTL_SET_ZERO_DATA issue REQ_OP_DISCARD that sd translates to WRITE SAME(16) UNMAP, reaching ata_scsi_write_same_xlat() without local shell access.
AC:LAttack complexity, low: On a 4Kn ATA device with TRIM (logical sector_size>2048), every block-layer discard deterministically hits WARN_ON(len>ATA_SCSI_RBUF_SIZE) in ata_format_dsm_trim_descr() then fails size!=sector_size. The attacker fully controls UNMAP/discard issuance; no race or uncontrollable memory layout is required.
PR:NPrivileges required, none: Unauthenticated iSCSI/NVMe-oF UNMAP and guest NFS/SMB hole-punch need no Linux UID or capability on the target. The same discard path is also reachable locally by an unprivileged writer via fallocate(PUNCH_HOLE) on discard-mounted filesystems, so Privileges Required is None rather than Low or High.
UI:NUser interaction, none: The attacker or ordinary storage clients issue UNMAP, NFSv4.2 DEALLOCATE, hole-punch, BLKDISCARD, or mount-discard/fstrim I/O themselves. No separate victim click, mount, or confirmation is required at exploit time.
S:UScope, unchanged: The WARN_ON splat, kernel log disclosure, and rejected TRIM remain inside the host kernel and the affected ATA device. The defect does not escape a VM, bypass an IOMMU/DMA boundary, or otherwise cross a separate security authority.
C:LConfidentiality impact, low: WARN_ON() (not WARN_ON_ONCE) calls warn_slowpath()/dump_stack() on every TRIM, disclosing kernel text addresses and limited layout in dmesg when kptr_restrict is relaxed. The rbuf length clamp prevents an out-of-bounds read, so this is not an arbitrary memory-disclosure primitive.
I:NIntegrity impact, none: After the warning, size!=sector_size takes invalid_param_len and returns a SCSI CHECK CONDITION without issuing DSM TRIM or writing kernel objects, user data, or device LBAs. Passthrough WRITE SAME is rejected, so there is no write or code-execution primitive.
A:HAvailability impact, high: WARN_ON() taints the kernel and panics when panic_on_warn is set or warn_limit is exceeded. Because it is not WARN_ON_ONCE, a remote initiator can repeat UNMAP to flood logs and force a host panic, and TRIM/discard is completely broken on 4Kn ATA volumes.