# CVE-2023-4806: Glibc: potential use-after-free in getaddrinfo()

> A rare use-after-free in glibc's getaddrinfo can cause application crashes when specific NSS modules and flags are used.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Sep 2023
- **Updated:** 14 Oct 2026
- **Also known as:** AZL-29954, AZL-34738, BELL-CVE-2023-4806, DEBIAN-CVE-2023-4806, GHSA-5f52-v49r-796w, ROOT-OS-DEBIAN-11-CVE-2023-4806

## What is CVE-2023-4806?

CVE-2023-4806 is a medium-severity use after free vulnerability in Fedoraproject Fedora, published on 18 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw has been identified in glibc. In an extremely rare situation, the getaddrinfo function may access memory that has been freed, resulting in an application crash. This issue is only exploitable when a NSS module implements only the _nss_*_gethostbyname2_r and _nss_*_getcanonname_r hooks without implementing the _nss_*_gethostbyname3_r hook. The resolved name should return a large number of IPv6 and IPv4, and the call to the getaddrinfo function should have the AF_INET6 address family with AI_CANONNAME, AI_ALL and AI_V4MAPPED as flags.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-4806?

It affects 22 products.


Products: Fedoraproject Fedora, Gnu Glibc, Redhat Codeready Linux Builder Eus, Redhat Codeready Linux Builder Eus for Power Little Endian, Redhat Codeready Linux Builder Eus for Power Little Endian Eus, Redhat Codeready Linux Builder for Arm64, Redhat Codeready Linux Builder for Arm64 Eus, Redhat Codeready Linux Builder for Ibm Z Systems, Redhat Codeready Linux Builder for Ibm Z Systems Eus, Redhat Enterprise Linux, Redhat Enterprise Linux Eus, Redhat Enterprise Linux for Arm 64, Redhat Enterprise Linux for Arm 64 Eus, Redhat Enterprise Linux for Ibm Z Systems, Redhat Enterprise Linux for Ibm Z Systems Eus, Redhat Enterprise Linux for Ibm Z Systems Eus S390x, Redhat Enterprise Linux for Ibm Z Systems S390x, Redhat Enterprise Linux for Power Little Endian, Redhat Enterprise Linux for Power Little Endian Eus, Redhat Enterprise Linux Server Aus and 2 more.

## How do I fix CVE-2023-4806?

Apply the vendor's patch.

## Is CVE-2023-4806 being exploited?

There is no known exploitation of CVE-2023-4806 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-4806 and fix it if it is affected.

What it is: CVE-2023-4806 is a medium-severity use after free vulnerability in Fedoraproject Fedora, published on 18 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-4806 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2023-4806/ (Markdown: https://insights.sbomify.com/CVE-2023-4806/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-4806
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-4806
- OSV: https://osv.dev/vulnerability/CVE-2023-4806

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-4806/
Summaries are generated and may contain mistakes; the official description above is the record.