# CVE-2026-43458: serial: caif: hold tty->link reference in ldisc_open and ser_release

> A use-after-free in the Linux kernel's CAIF serial driver allows attackers to trigger memory corruption, potentially leading to code execution or system crashes.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 8 May 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-43458, DEBIAN-CVE-2026-43458, GHSA-27j8-6q5h-m6jx, ROOT-OS-DEBIAN-11-CVE-2026-43458, ROOT-OS-UBUNTU-2204-CVE-2026-43458, ROOT-OS-UBUNTU-2404-CVE-2026-43458, UBUNTU-CVE-2026-43458

## What is CVE-2026-43458?

CVE-2026-43458 is a high-severity use after free vulnerability in Linux kernel, published on 8 May 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: caif: hold tty->link reference in ldisc_open and ser_release

A reproducer triggers a KASAN slab-use-after-free in pty_write_room()
when caif_serial's TX path calls tty_write_room(). The faulting access
is on tty->link->port.

Hold an extra kref on tty->link for the lifetime of the caif_serial line
discipline: get it in ldisc_open() and drop it in ser_release(), and
also drop it on the ldisc_open() error path.

With this change applied, the reproducer no longer triggers the UAF in
my testing.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-43458?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43458?

Apply the vendor's patch.

## Is CVE-2026-43458 being exploited?

There is no known exploitation of CVE-2026-43458 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-2026-43458 and fix it if it is affected.

What it is: CVE-2026-43458 is a high-severity use after free vulnerability in Linux kernel, published on 8 May 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-2026-43458 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-2026-43458/ (Markdown: https://insights.sbomify.com/CVE-2026-43458/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43458
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43458
- OSV: https://osv.dev/vulnerability/CVE-2026-43458

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43458/
Summaries are generated and may contain mistakes; the official description above is the record.