Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
yhirose cpp-httplib — cpp-httplib: Malicious `X-Forwarded-For` Under Trusted-Proxy Configuration Triggers Empty `vector::front()`, Leading to Undefined Behavior and Server Crash
AV AC AT PR UI VC VI VA CVSS EPSS %ile KEV
N L N N N N N H 8.7 .0033 25.7 —
AFFECTED
Product Versions Fixed
cpp-httplib < 0.44.0 – —
TIMELINE
May 14 Reserved by GitHub_M
May 29 EXPLOIT PUBLISHED — CVE-2026-46527 (yhirose cpp-httplib). Public exploit reference added.
May 29 Published (CNA: GitHub_M)
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.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
|---|
| May 14, 2026 | Reserved | Reserved by GitHub_M |
| May 29, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-46527 (yhirose cpp-httplib). Public exploit reference added. |
| May 29, 2026 | Published | Published (CNA: GitHub_M) |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| yhirose | cpp-httplib | — | < 0.44.0 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-46527 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.