# CVE-2026-23115: serial: Fix not set tty->port race condition

> A race condition in the Linux kernel serial driver allows user-space to trigger a kernel crash by opening a console before the TTY port is linked.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Feb 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-23115, DEBIAN-CVE-2026-23115, GHSA-mwgw-4c23-7465, UBUNTU-CVE-2026-23115

## What is CVE-2026-23115?

CVE-2026-23115 is a medium-severity vulnerability in Linux kernel, published on 14 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

serial: Fix not set tty->port race condition

Revert commit bfc467db60b7 ("serial: remove redundant
tty_port_link_device()") because the tty_port_link_device() is not
redundant: the tty->port has to be confured before we call
uart_configure_port(), otherwise user-space can open console without TTY
linked to the driver.

This tty_port_link_device() was added explicitly to avoid this exact
issue in commit fb2b90014d78 ("tty: link tty and port before configuring
it as console"), so offending commit basically reverted the fix saying
it is redundant without addressing the actual race condition presented
there.

Reproducible always as tty->port warning on Qualcomm SoC with most of
devices disabled, so with very fast boot, and one serial device being
the console:

  printk: legacy console [ttyMSM0] enabled
  printk: legacy console [ttyMSM0] enabled
  printk: legacy bootconsole [qcom_geni0] disabled
  printk: legacy bootconsole [qcom_geni0] disabled
  ------------[ cut here ]------------
  tty_init_dev: ttyMSM driver does not set tty->port. This would crash the kernel. Fix the driver!
  WARNING: drivers/tty/tty_io.c:1414 at tty_init_dev.part.0+0x228/0x25c, CPU#2: systemd/1
  Modules linked in: socinfo tcsrcc_eliza gcc_eliza sm3_ce fuse ipv6
  CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G S                  6.19.0-rc4-next-20260108-00024-g2202f4d30aa8 #73 PREEMPT
  Tainted: [S]=CPU_OUT_OF_SPEC
  Hardware name: Qualcomm Technologies, Inc. Eliza (DT)
  ...
  tty_init_dev.part.0 (drivers/tty/tty_io.c:1414 (discriminator 11)) (P)
  tty_open (arch/arm64/include/asm/atomic_ll_sc.h:95 (discriminator 3) drivers/tty/tty_io.c:2073 (discriminator 3) drivers/tty/tty_io.c:2120 (discriminator 3))
  chrdev_open (fs/char_dev.c:411)
  do_dentry_open (fs/open.c:962)
  vfs_open (fs/open.c:1094)
  do_open (fs/namei.c:4634)
  path_openat (fs/namei.c:4793)
  do_filp_open (fs/namei.c:4820)
  do_sys_openat2 (fs/open.c:1391 (discriminator 3))
  ...
  Starting Network Name Resolution...

Apparently the flow with this small Yocto-based ramdisk user-space is:

driver (qcom_geni_serial.c):                  user-space:
============================                  ===========
qcom_geni_serial_probe()
 uart_add_one_port()
  serial_core_register_port()
   serial_core_add_one_port()
    uart_configure_port()
     register_console()
    |
    |                                         open console
    |                                          ...
    |                                          tty_init_dev()
    |                                           driver->ports[idx] is NULL
    |
    tty_port_register_device_attr_serdev()
     tty_port_link_device() <- set driver->ports[idx]

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-23115?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23115?

Apply the vendor's patch.

## Is CVE-2026-23115 being exploited?

There is no known exploitation of CVE-2026-23115 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23115 and fix it if it is affected.

What it is: CVE-2026-23115 is a medium-severity vulnerability in Linux kernel, published on 14 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-23115 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-23115/ (Markdown: https://insights.sbomify.com/CVE-2026-23115/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23115
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23115
- OSV: https://osv.dev/vulnerability/CVE-2026-23115

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23115/
Summaries are generated and may contain mistakes; the official description above is the record.