Fluid Attacks Database

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.

Mitigation

Update Impact

Minimal update. May introduce new vulnerabilities or breaking changes.

Ecosystem	Package	Affected version	Patched versions
debian 12	cpp-httplib	=0.11.4+ds-1 \|\| =0.11.4+ds-1+deb12u1 \|\| =0.11.4+ds-2 \|\| =0.11.4+ds-3 \|\| =0.13.1+ds-1 \|\| =0.14.0+ds-1 \|\| =0.14.1+ds-1 \|\| =0.14.1+ds-2 \|\| =0.14.2+ds-1 \|\| =0.14.3+ds-1 \|\| =0.14.3+ds-1.1 \|\| =0.14.3+ds-1.1~exp1 \|\| =0.15.3+ds-1 \|\| =0.15.3+ds-2 \|\| =0.15.3+ds-3 \|\| =0.16.0+ds-1 \|\| =0.16.3+ds-1 \|\| =0.16.3+ds-2 \|\| =0.18.0+ds-1 \|\| =0.18.7-1 \|\| =0.20.1+ds-3 \|\| =0.25.0+ds-1 \|\| =0.26.0+ds-2 \|\| =0.41.0+ds-1 \|\| =0.41.0+ds-2 \|\| =0.41.0+ds-3	-
debian 14	cpp-httplib	=0.18.7-1 \|\| =0.20.1+ds-3 \|\| =0.25.0+ds-1 \|\| =0.26.0+ds-2 \|\| =0.41.0+ds-1 \|\| =0.41.0+ds-2 \|\| >=0 <0.41.0+ds-3	0.41.0+ds-3
debian 13	cpp-httplib	=0.18.7-1 \|\| =0.18.7-1+deb13u1 \|\| =0.20.1+ds-3 \|\| =0.25.0+ds-1 \|\| =0.26.0+ds-2 \|\| =0.41.0+ds-1 \|\| =0.41.0+ds-2 \|\| =0.41.0+ds-3	-

Aliases

1. CVE-2026-284342. NVD-2026-284343. OSV-DEBIAN-2026-284344. OSV-2026-284345. SECURITY-TRACKER-CVE-2026-28434

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