# CVE-2023-38039: Denial of service in curl

> A malicious server can cause curl to exhaust heap memory by sending endless headers, leading to a denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/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:** 15 Sep 2023
- **Updated:** 2 Dec 2025
- **Also known as:** ALPINE-CVE-2023-38039, AZL-28833, AZL-29698, AZL-38341, BELL-CVE-2023-38039, CLEANSTART-2026-UC65166, CURL-CVE-2023-38039, DEBIAN-CVE-2023-38039, ECHO-59f8-35ac-3474, GHSA-99j9-jf36-9747, JLSEC-2026-1342, SUSE-SU-2023:3692-1, SUSE-SU-2023:3823-1, UBUNTU-CVE-2023-38039, openSUSE-SU-2024:13230-1

## What is CVE-2023-38039?

CVE-2023-38039 is a high-severity denial of service vulnerability in Fedoraproject Fedora, published on 15 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When curl retrieves an HTTP response, it stores the incoming headers so that
they can be accessed later via the libcurl headers API.

However, curl did not have a limit in how many or how large headers it would
accept in a response, allowing a malicious server to stream an endless series
of headers and eventually cause curl to run out of heap memory.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2023-38039?

It affects 10 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `curl` | SUSE:Linux Enterprise Micro 5.3 | All versions | 8.0.1-150400.5.29.1 |
| `curl` | SUSE:Linux Enterprise Micro 5.4 | All versions | 8.0.1-150400.5.29.1 |
| `curl` | SUSE:Linux Enterprise Module for Basesystem 15 SP4 | All versions | 8.0.1-150400.5.29.1 |
| `curl` | SUSE:Linux Enterprise Module for Basesystem 15 SP5 | All versions | 8.0.1-150400.5.29.1 |
| `curl` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 8.0.1-11.71.1 |
| `curl` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 8.0.1-11.71.1 |
| `curl` | SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 8.0.1-11.71.1 |
| `curl` | openSUSE:Leap 15.4 | All versions | 8.0.1-150400.5.29.1 |
| `curl` | openSUSE:Leap 15.5 | All versions | 8.0.1-150400.5.29.1 |
| `curl` | openSUSE:Tumbleweed | All versions | 8.3.0-1.1 |

Products: Fedoraproject Fedora, Haxx Curl, Microsoft Windows 10 1809, Microsoft Windows 10 21h2, Microsoft Windows 10 22h2, Microsoft Windows 11 21h2, Microsoft Windows 11 22h2, Microsoft Windows 11 23h2, Microsoft Windows Server 2019, Microsoft Windows Server 2022.

## How do I fix CVE-2023-38039?

Upgrade to a fixed version.

## Is CVE-2023-38039 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-38039 exists.

Public exploit code:

- For all vicarius.io/vsoviety analysis (github_poc): https://github.com/Smartkeyss/CVE-2023-38039

## 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-2023-38039 and fix it if it is affected.

What it is: CVE-2023-38039 is a high-severity denial of service vulnerability in Fedoraproject Fedora, published on 15 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-38039 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-2023-38039/ (Markdown: https://insights.sbomify.com/CVE-2023-38039/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-38039
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-38039
- OSV: https://osv.dev/vulnerability/CVE-2023-38039

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-38039/
Summaries are generated and may contain mistakes; the official description above is the record.