CVE-2023-27535
Published: August 31, 2023Last modified: December 15, 2025
Description
An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However, certain FTP settings such as CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC, and CURLOPT_USE_SSL were not included in the configuration match checks, causing them to match too easily. This could lead to libcurl using the wrong credentials when performing a transfer, potentially allowing unauthorized access to sensitive information.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 5.9 |
| Attack Vector | NETWORK |
| Attack complexity | HIGH |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity impact | NONE |
| Availability impact | NONE |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | curl | Not affected (8.2.1-r0) |
| Stream | curl | Not affected (8.2.1-r0) | |
| Hardened Containers | Stream | curl | Not affected (8.2.1-r0) |
References
- https://hackerone.com/reports/1892780
- https://lists.debian.org/debian-lts-announce/2023/04/msg00025.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36NBD5YLJXXEDZLDGNFCERWRYJQ6LAQW/
- https://lists.fedoraproject.org/archives/list/[email protected]/message/36NBD5YLJXXEDZLDGNFCERWRYJQ6LAQW/
- https://security.gentoo.org/glsa/202310-12
- https://security.netapp.com/advisory/ntap-20230420-0010/