# CVE-2023-27536: Auth bypass in https://github.com/curl/curl

> Attackers can bypass authentication in libcurl by exploiting connection reuse flaws in GSSAPI transfers, potentially accessing sensitive information.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **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-2023-27536, AZL-25785, AZL-25802, AZL-25809, AZL-25845, AZL-34606, AZL-38476, CLEANSTART-2026-IP69677, CURL-CVE-2023-27536, DEBIAN-CVE-2023-27536, GHSA-4f9f-mpmj-4c52, JLSEC-2025-30, UBUNTU-CVE-2023-27536

## What is CVE-2023-27536?

CVE-2023-27536 is a medium-severity authentication bypass vulnerability in Debian Debian Linux, published on 30 Mar 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An authentication bypass vulnerability exists libcurl <8.0.0 in the connection reuse feature which can reuse previously established connections with incorrect user permissions due to a failure to check for changes in the CURLOPT_GSSAPI_DELEGATION option. This vulnerability affects krb5/kerberos/negotiate/GSSAPI transfers and could potentially result in unauthorized access to sensitive information. The safest option is to not reuse connections if the CURLOPT_GSSAPI_DELEGATION option has been changed.

Weakness: CWE-287 (Improper Authentication), CWE-305 (Authentication Bypass by Primary Weakness)

## Which versions are affected by CVE-2023-27536?

It affects 10 products.


Products: Debian Debian Linux, Fedoraproject Fedora, Haxx Libcurl, Netapp Active Iq Unified Manager, Netapp H300s Firmware, Netapp H410s Firmware, Netapp H500s Firmware, Netapp H700s Firmware, Netapp Ontap, Splunk Universal Forwarder.

## How do I fix CVE-2023-27536?

Upgrade to a fixed version.

## Is CVE-2023-27536 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-27536 exists.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-27536 and fix it if it is affected.

What it is: CVE-2023-27536 is a medium-severity authentication bypass vulnerability in Debian Debian Linux, 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-2023-27536 exists.

Affected product: Debian Debian 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-2023-27536/ (Markdown: https://insights.sbomify.com/CVE-2023-27536/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-27536
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-27536
- OSV: https://osv.dev/vulnerability/CVE-2023-27536

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-27536/
Summaries are generated and may contain mistakes; the official description above is the record.