CVE-2023-27535

Publication date 20 March 2023

Last updated 26 August 2025

Ubuntu priority

Cvss 3 Severity Score

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
curl	23.04 lunar	Fixed 7.88.1-6ubuntu2
	22.10 kinetic	Fixed 7.85.0-1ubuntu0.5
	22.04 LTS jammy	Fixed 7.81.0-1ubuntu1.10
	20.04 LTS focal	Fixed 7.68.0-1ubuntu2.18
	18.04 LTS bionic	Fixed 7.58.0-2ubuntu3.24
	16.04 LTS xenial	Fixed 7.47.0-1ubuntu2.19+esm8
	14.04 LTS trusty	Fixed 7.35.0-1ubuntu2.20+esm15

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Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
curl	Upstream: 8f46084

Severity score breakdown

Parameter	Value
Base score	5.9 · Medium
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