CVE-2026-46527 - cpp-httplib: Malicious `X-Forwarded-For` Under Trusted-Proxy Configuration Triggers Empty `vector::front()`, Leading to Undefined Behavior and Server Crash

CVE-2026-46527 - cpp-httplib: Malicious `X-Forwarded-For` Under Trusted-Proxy Configuration Triggers Empty `vector::front()`, Leading to Undefined Behavior and Server Crash

https://cvefeed.io/rssfeed/latest.atom / Fri, 05/29/2026 - 23:26
CVE ID :CVE-2026-46527
Published : May 29, 2026, 8:16 p.m. | 45 minutes ago
Description :cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_proxies() with a non-empty trusted-proxy list, an attacker can send an HTTP request that includes an X-Forwarded-For header whose value parses to no valid IP segments. The code path then executes get_client_ip(), which calls front() on an empty std::vector—undefined behavior in C++. On typical implementations this manifests as abnormal process termination (denial of service). With Sanitizers enabled, you get an explicit runtime diagnostic. This vulnerability is fixed in 0.44.0.
Severity: 8.7 | HIGH
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Kenya Education Network CERT(KENET-CERT) is a Cybersecurity Emergency Response Team and Co-ordination Center operated by the National Research and Education Network of Kenya. KENET-CERT coordination center promotes awareness on cybersecurity incidences as well as coordinates and assists member institutions in responding effectively to cyber security threats and incidences. KENET-CERT works closely with Kenya's National CIRT coordination center (CIRT/CC) as a sector CIRT for the academic institutions. KENET promotes use of ICT in Teaching, Learning and Research in Higher Education Institutions in Kenya. KENET aims to interconnect all the Universities, Tertiary and Research Institutions in Kenya by setting up a cost effective and sustainable private network with high speed access to the global Internet. KENET also facilitates electronic communication among students and faculties in member institutions, share learning and teaching resources by collaboration in Research and Development of Educational content.