Description
HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure's drl field that allows buffer misparse as new FCGI record headers. When contentLength is 65535 and paddingLength is 1 or more, the drl field wraps to 0, causing incorrect record consumption and allowing malicious FastCGI backends to desynchronize the FCGI framing parser, potentially causing request routing errors, response smuggling, or memory safety issues.
CVSS breakdown
CVSS 4.0
Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality (Vulnerable System)
None
Integrity (Vulnerable System)
High
Availability (Vulnerable System)
None
Confidentiality (Subsequent System)
Low
Integrity (Subsequent System)
High
Availability (Subsequent System)
None
CVSS 3.1
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
None
Affected products
- haproxy / haproxy0 – 3.4.0
- haproxy / haproxy5985276735777634d8c85f1d73bb7764aab0d6dd – 5985276735777634d8c85f1d73bb7764aab0d6dd