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Vulnerability record · CVE-2023-27536 · published 30 March 2023

CVE-2023-27536: Haxx libcurl improper authentication vulnerability

Haxx · Libcurl

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.

5.9 CVSS 3.1 Medium EPSS 1.6% · top 25.7% CWE-305 · CWE-305CWE-287 · Improper authentication
5.9CVSS 3.1 base score
1.6%EPSS exploitation probability, 30 days
NoNot in CISA KEV
10Affected product versions listed by NVD
10References, 2 tagged exploit
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

10 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://hackerone.com/reports/1895135 ExploitThird Party Advisory
https://lists.debian.org/debian-lts-announce/2023/04/msg00025.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36NBD5YLJXXEDZLDGNFCERW Mailing ListThird Party Advisory
https://security.gentoo.org/glsa/202310-12 Third Party Advisory
https://security.netapp.com/advisory/ntap-20230420-0010/ Third Party Advisory
https://hackerone.com/reports/1895135 ExploitThird Party Advisory
https://lists.debian.org/debian-lts-announce/2023/04/msg00025.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36NBD5YLJXXEDZLDGNFCERW Mailing ListThird Party Advisory
https://security.gentoo.org/glsa/202310-12 Third Party Advisory
https://security.netapp.com/advisory/ntap-20230420-0010/ Third Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2023-27536), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.