# CVE-2023-27533: Command injection in https://github.com/curl/curl

> Attackers can execute arbitrary code via malicious TELNET input in curl due to insufficient input validation during server negotiation.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Mar 2023
- **Updated:** 14 Oct 2026
- **Also known as:** ALPINE-CVE-2023-27533, AZL-25783, AZL-25804, AZL-25812, AZL-25894, AZL-34608, AZL-37878, CLEANSTART-2026-RI66182, CLSA-2026-1777463367, CLSA-2026-1777463593, CURL-CVE-2023-27533, DEBIAN-CVE-2023-27533, ECHO-2cba-07b8-6862, GHSA-xvw3-6q4f-2gcv, JLSEC-2026-405, UBUNTU-CVE-2023-27533

## What is CVE-2023-27533?

CVE-2023-27533 is a critical command injection vulnerability in Fedoraproject Fedora, published on 30 Mar 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in input validation exists in curl <8.0 during communication using the TELNET protocol may allow an attacker to pass on maliciously crafted user name and "telnet options" during server negotiation. The lack of proper input scrubbing allows an attacker to send content or perform option negotiation without the application's intent. This vulnerability could be exploited if an application allows user input, thereby enabling attackers to execute arbitrary code on the system.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), CWE-75 (Failure to Sanitize Special Elements into a Different Plane)

## Which versions are affected by CVE-2023-27533?

It affects 9 products.


Products: Fedoraproject Fedora, Haxx Curl, Netapp Active Iq Unified Manager, Netapp Clustered Data Ontap, Netapp H300s Firmware, Netapp H410s Firmware, Netapp H500s Firmware, Netapp H700s Firmware, Splunk Universal Forwarder.

## How do I fix CVE-2023-27533?

Upgrade to a fixed version.

## Is CVE-2023-27533 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-27533 exists.

## 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-2023-27533 and fix it if it is affected.

What it is: CVE-2023-27533 is a critical command injection vulnerability in Fedoraproject Fedora, published on 30 Mar 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-2023-27533 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-2023-27533/ (Markdown: https://insights.sbomify.com/CVE-2023-27533/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-27533
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-27533
- OSV: https://osv.dev/vulnerability/CVE-2023-27533

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-27533/
Summaries are generated and may contain mistakes; the official description above is the record.