Is CVE-2026-28434 actively exploited?

No active exploitation of CVE-2026-28434 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-28434 be exploited remotely?

Yes. CVE-2026-28434 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-28434?

CVE-2026-28434 has a CVSS score of 5.3 (MEDIUM).

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MEDIUM

CVE-2026-28434

CWE-200Published: March 4, 2026· Updated: Mar 5, 2026

5.3

CVSS v3.1

EPSS:0.04%probability of exploitation in 30 daysPercentile:12.6th

Official Description

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.

NVD Source

Technical Analysis

CVE-2026-28434 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

From a weakness classification perspective (CWE-200): Information exposure vulnerabilities leak sensitive data to unauthorized actors.