# CVE-2023-6246: Glibc: heap-based buffer overflow in __vsyslog_internal()

> A heap-based buffer overflow in glibc's syslog function allows local attackers to cause crashes or escalate privileges.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Jan 2024
- **Updated:** 14 Oct 2026
- **Also known as:** AZL-34735, BELL-CVE-2023-6246, DEBIAN-CVE-2023-6246, GHSA-p6rw-gvvh-q8v4, UBUNTU-CVE-2023-6246, openSUSE-SU-2024:13647-1

## What is CVE-2023-6246?

CVE-2023-6246 is a high-severity memory corruption vulnerability in Fedoraproject Fedora, published on 31 Jan 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A heap-based buffer overflow was found in the __vsyslog_internal function of the glibc library. This function is called by the syslog and vsyslog functions. This issue occurs when the openlog function was not called, or called with the ident argument set to NULL, and the program name (the basename of argv[0]) is bigger than 1024 bytes, resulting in an application crash or local privilege escalation. This issue affects glibc 2.36 and newer.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2023-6246?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `glibc` | openSUSE:Tumbleweed | All versions | 2.39-1.2 |

Products: Fedoraproject Fedora, Gnu Glibc.

## How do I fix CVE-2023-6246?

Apply the vendor's patch.

## Is CVE-2023-6246 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-6246 exists.

Public exploit code:

- https://github.com/elpe-pinillo/CVE-2023-6246 (github_poc): https://github.com/elpe-pinillo/CVE-2023-6246
- CVE-2023-6246 glibc __vsyslog_internal() heap buffer overflow exploitation using Convergent Time Theory (α = 0.0302011). 33-layer temporal heap spray + phase-locked trigger for reliable local privilege escalation. (github_poc): https://github.com/SimoesCTT/CTT-Vsyslog-Vortex-CVE-2023-6246

## 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-2023-6246 and fix it if it is affected.

What it is: CVE-2023-6246 is a high-severity memory corruption vulnerability in Fedoraproject Fedora, published on 31 Jan 2024. 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-2023-6246 exists.

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-2023-6246/ (Markdown: https://insights.sbomify.com/CVE-2023-6246/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-6246
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-6246
- OSV: https://osv.dev/vulnerability/CVE-2023-6246

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-6246/
Summaries are generated and may contain mistakes; the official description above is the record.