# CVE-2023-53123: PCI: s390: Fix use-after-free of PCI resources with per-function hotplug

> A use-after-free vulnerability in the Linux kernel's s390 PCI subsystem allows attackers to cause denial of service or execute code via hotplug operations.

- **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:** 2 May 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-53123, DEBIAN-CVE-2023-53123, GHSA-3m8v-mqfw-xp3g, UBUNTU-CVE-2023-53123

## What is CVE-2023-53123?

CVE-2023-53123 is a high-severity use after free vulnerability in Linux kernel, published on 2 May 2025. 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:

PCI: s390: Fix use-after-free of PCI resources with per-function hotplug

On s390 PCI functions may be hotplugged individually even when they
belong to a multi-function device. In particular on an SR-IOV device VFs
may be removed and later re-added.

In commit a50297cf8235 ("s390/pci: separate zbus creation from
scanning") it was missed however that struct pci_bus and struct
zpci_bus's resource list retained a reference to the PCI functions MMIO
resources even though those resources are released and freed on
hot-unplug. These stale resources may subsequently be claimed when the
PCI function re-appears resulting in use-after-free.

One idea of fixing this use-after-free in s390 specific code that was
investigated was to simply keep resources around from the moment a PCI
function first appeared until the whole virtual PCI bus created for
a multi-function device disappears. The problem with this however is
that due to the requirement of artificial MMIO addreesses (address
cookies) extra logic is then needed to keep the address cookies
compatible on re-plug. At the same time the MMIO resources semantically
belong to the PCI function so tying their lifecycle to the function
seems more logical.

Instead a simpler approach is to remove the resources of an individually
hot-unplugged PCI function from the PCI bus's resource list while
keeping the resources of other PCI functions on the PCI bus untouched.

This is done by introducing pci_bus_remove_resource() to remove an
individual resource. Similarly the resource also needs to be removed
from the struct zpci_bus's resource list. It turns out however, that
there is really no need to add the MMIO resources to the struct
zpci_bus's resource list at all and instead we can simply use the
zpci_bar_struct's resource pointer directly.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-53123?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53123?

Apply the vendor's patch.

## Is CVE-2023-53123 being exploited?

There is no known exploitation of CVE-2023-53123 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-2023-53123 and fix it if it is affected.

What it is: CVE-2023-53123 is a high-severity use after free vulnerability in Linux kernel, published on 2 May 2025. 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-2023-53123 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-2023-53123/ (Markdown: https://insights.sbomify.com/CVE-2023-53123/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53123
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53123
- OSV: https://osv.dev/vulnerability/CVE-2023-53123

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53123/
Summaries are generated and may contain mistakes; the official description above is the record.