# CVE-2016-4558: Use after free in n/a

> Local attackers can trigger a use-after-free in the Linux kernel BPF subsystem, causing denial of service or potential code execution.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/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:** 23 May 2016
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2016-4558, GHSA-283c-4h8h-4xmp, UBUNTU-CVE-2016-4558

## What is CVE-2016-4558?

CVE-2016-4558 is a high-severity use after free vulnerability in Canonical Ubuntu Linux, published on 23 May 2016. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The BPF subsystem in the Linux kernel before 4.5.5 mishandles reference counts, which allows local users to cause a denial of service (use-after-free) or possibly have unspecified other impact via a crafted application on (1) a system with more than 32 Gb of memory, related to the program reference count or (2) a 1 Tb system, related to the map reference count.

## Which versions are affected by CVE-2016-4558?

It affects 2 products.


Products: Canonical Ubuntu Linux, Linux kernel.

## How do I fix CVE-2016-4558?

Apply the vendor's patch.

## Is CVE-2016-4558 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2016-4558 exists.

Public exploit code:

- Linux Kernel (Ubuntu 16.04) - Reference Count Overflow Using BPF Maps (exploitdb)

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-4558 and fix it if it is affected.

What it is: CVE-2016-4558 is a high-severity use after free vulnerability in Canonical Ubuntu Linux, published on 23 May 2016. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2016-4558 exists.

Affected product: Canonical Ubuntu Linux. 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-2016-4558/ (Markdown: https://insights.sbomify.com/CVE-2016-4558/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-4558
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-4558
- OSV: https://osv.dev/vulnerability/CVE-2016-4558

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From sbomify Insights: https://insights.sbomify.com/CVE-2016-4558/
Summaries are generated and may contain mistakes; the official description above is the record.