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CVE-2026-28434

MEDIUM CVSS 3.1: 5.3 EPSS 0.10%
Updated Mar 05, 2026
Yhirose
Parameter Value
CVSS 5.3 (MEDIUM)
Affected Versions before 0.35.0
Fixed In 0.35.0
Type CWE-200 (Information Exposure)
Vendor Yhirose
Public PoC No

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.35.0, when a request handler throws a C++ exception and the application has not registered a custom exception handler via set_exception_handler(), the library catches the exception and writes its message directly into the HTTP response as a header named EXCEPTION_WHAT. This header is sent to whoever made the request, with no authentication check and no special configuration required to trigger it.

The behavior is on by default. A developer who does not know to opt in to set_exception_handler() will ship a server that leaks internal exception messages to any client. This vulnerability is fixed in 0.35.0.

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
None
No data modification
Availability
None
No disruption

CVSS Vector v3.1

Weakness Type (CWE)

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Yhirose Cpp-Httplib
cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*
0.35.0