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CVE-2026-90008
scsi: megaraid_sas: Limit NVMe request size to the PRP chain frame
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/scsi. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-90008 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| 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. |
The vulnerability
What the bug is
megasas_make_prp_nvme() builds a command's PRP list in cmd->sg_frame, a DMA pool buffer of instance->max_chain_frame_sz bytes, spending one entry per NVMe page of the transfer plus one per page of the buffer for the chain pointer. The loop runs until the transfer is described and never checks the buffer bound. max_hw_sectors comes straight from the MDTS the firmware reports for the drive. On drives with a large MDTS the only thing keeping the list inside the buffer was the block layer default of 1280 KiB, which needs 320 entries, which fit into a 4 KiB frame as that holds 512. But since commit 9b8b84879d4a ("block: Increase BLK_DEF_MAX_SECTORS_CAP") that default is 4 MiB, and such a transfer needs 1025 entries, so the list runs a full page past the end of the frame: sd 1:0:1:0: [sdb] tag#630 page boundary ptr_sgl: 0x00000000ba62d13f BUG: unable to handle page fault for address: ff663bcb81e7c000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page RIP: 0010:megasas_build_and_issue_cmd_fusion+0xeaa/0x1870 [megaraid_sas] If the page after the frame happens to be mapped, the overrun does not fault but silently corrupts the neighbouring pool entry, which is another in-flight command's PRP list. Cap max_hw_sectors at what the chain frame can describe, less one page for transfers that do not start on a page boundary and so need one entry more. This is the megaraid_sas counterpart of commit 04631f55afc5 ("scsi: mpt3sas: Limit NVMe request size to 2 MiB"), but derives the limit from max_chain_frame_sz rather than hardcoding it.
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/scsi/megaraid/megaraid_sas_base.c
- What this is
- MEGARAID SCSI/SAS DRIVERSMAINTAINERS section matched on drivers/scsi/megaraid/ · megaraidlinux.pdl@broadcom.com · Maintained
- Kernel module
- megaraid_sas
Check it on the machine
grep -wE 'CONFIG_MEGARAID_NEWGEN|CONFIG_MEGARAID_SAS' /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 megaraid_sasPrints 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, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/cloud-amd64, arm64/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
- trixieMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, riscv64/riscv64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_MEGARAID_NEWGEN, CONFIG_MEGARAID_SAS
- Reads as
- all on means the file is compiled; any one off means it is not.
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
Signals
- Published
- 2026-09-16 (33 days ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 6.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/scsi
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.17 | 6.18.51 | 4bb34769ef44 |
| 6.17 | 7.2.5 | 4dd118d06dec |
| 6.17 | 7.3 | af8c27375733 |
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:LAttack vector, local
- The overflow is in megaraid_sas while building NVMe PRP lists for SCSI commands from the local block layer (queuecommand → megasas_build_and_issue_cmd_fusion → megasas_make_prp_nvme); the HBA driver is not bound to the network stack.
- AC:LAttack complexity, low
- On MegaRAID NVMe Fast Path with a firmware MDTS above the 4 KiB chain-frame capacity, a single 4 MiB I/O (the post-6.17 block-layer default) drives the unbounded PRP loop past cmd->sg_frame with no race or other condition outside the attacker’s control.
- PR:LPrivileges required, low
- An unprivileged local user who can read or write a file or block device on the NVMe-backed volume can submit a large O_DIRECT or sequential I/O that the block layer issues as one request; the megaraid ioctl CAP_SYS_ADMIN check is not on this path.
- UI:NUser interaction, none
- The attacker triggers the overflow directly by submitting their own I/O; no separate victim action is required.
- S:UScope, unchanged
- The out-of-bounds write corrupts host-kernel DMA-pool memory of the same HBA; it is not a VM escape, IOMMU bypass, or other cross-authority impact.
- C:HConfidentiality impact, high
- The write overruns the PRP chain frame into the neighbouring dma_pool object, another in-flight command’s PRP list, so DMA can be redirected to attacker-controlled buffers and disclose other I/O or kernel memory.
- I:HIntegrity impact, high
- This is an unbounded out-of-bounds write of DMA addresses past a fixed-size sg_frame, corrupting adjacent kernel/DMA-pool memory and enabling integrity violation and control-flow or DMA hijacking.
- A:HAvailability impact, high
- When the page after the frame is unmapped the overrun causes a kernel page-fault oops in megasas_build_and_issue_cmd_fusion, as documented in the fix; neighbouring-command corruption can also panic or hang the host.