curl would wrongly reuse an existing HTTP proxy connection doing CONNECT to a
server, even if the new request uses different credentials for the HTTP proxy.
The proper behavior is to create or use a separate connection.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://curl.se/docs/CVE-2026-3784.html
2499f714-1537-4658-8207-48ae4bb9eae9
https://curl.se/docs/CVE-2026-3784.json
2499f714-1537-4658-8207-48ae4bb9eae9
https://hackerone.com/reports/3584903
2499f714-1537-4658-8207-48ae4bb9eae9
http://www.openwall.com/lists/oss-security/2026/03/11/3
af854a3a-2127-422b-91ae-364da2661108