Information disclosure in Yhirose Cpp-Httplib
CVE-2026-28434
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.
Vulnerability class: Information Disclosure
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.004 (35.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- Yhirose Cpp-Httplib — versions < 0.35.0
Weakness classification (CWE)
References
- github.com/yhirose/cpp-httplib/security/advisories/GHSA-8mpw-r4gc-xm7q (Exploit, Mitigation, Vendor Advisory)
- github.com/yhirose/cpp-httplib/commit/defd907c7469c5c8281247b73bbd07be24c31164 (Patch)
Frequently asked questions
- What is CVE-2026-28434?
- CVE-2026-28434 is a medium-severity vulnerability in Yhirose Cpp-Httplib, classified under Information Disclosure. CVSS score: 5.3/10. Published 2026-03-04.
- How severe is CVE-2026-28434?
- Medium severity. CVSS v3 base score is 5.3 out of 10.