CVE-2026-28434
MEDIUMDescription
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.
How to fix
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 22% of all known CVEs.
References
Related Vulnerabilities
Other CWE-200 (Information Exposure) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-24919 | High | 8.6 | 100% | KEV + Ransom | - |
| CVE-2020-14181 | Medium | 5.3 | 100% | - | Fix |
| CVE-2021-34429 | Medium | 5.3 | 99% | - | Fix |
| CVE-2018-11409 | Medium | 5.3 | 98% | - | - |
| CVE-2021-41277 | Critical | 10.0 | 97% | KEV | - |
| CVE-2016-2183 | High | 7.5 | 96% | - | Fix |
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Start freeThis product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-05.