CVE-2026-46527
CVE-2026-46527 · cpp-httplib: Malicious `X-Forwarded-For` Under Trusted-Proxy Configuration Triggers Empty `vector::front()`, Leading to Undefined Behavior and Server Crash
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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.
CVSS 8.7 · High · EPSS 0.3%
- Published
- Updated
Stack: system
Affected products and versions
cpp-httplib
- Versions
- < 0.44.0: Affected
No fix published
cpp-httplib Debian:12
- Versions
- 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
- 0.41.0+ds-3~bpo13+1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
cpp-httplib Debian:13
- Versions
- 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
- 0.41.0+ds-3~bpo13+1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
cpp-httplib Debian:14
- Versions
- 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
- 0.41.0+ds-3~bpo13+1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
cpp-httplib Ubuntu:Pro:22.04:LTS
- Versions
- 0.9.9+ds-1
- 0.9.10+ds-1
- 0.10.1+ds-1
- 0.10.2+ds-1
- 0.10.3+ds-1
- 0.10.3+ds-1ubuntu0.1~esm1
- 0.10.3+ds-1ubuntu0.1~esm2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
cpp-httplib Ubuntu:Pro:24.04:LTS
- Versions
- 0.13.1+ds-1ubuntu1
- 0.14.3+ds-1
- 0.14.3+ds-1.1
- 0.14.3+ds-1.1build1
- 0.14.3+ds-1.1build2
- 0.14.3+ds-1.1ubuntu0.1~esm1
- 0.14.3+ds-1.1ubuntu0.1~esm2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
cpp-httplib Ubuntu:25.10
- Versions
- 0.18.7-1
- 0.18.7-1ubuntu0.25.10.1
- 0.18.7-1ubuntu0.25.10.2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
cpp-httplib Ubuntu:26.10
- Versions
- 0.26.0+ds-2ubuntu3
- 0.26.0+ds-2ubuntu4
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
cpp-httplib Ubuntu:Pro:26.04:LTS
- Versions
- 0.18.7-1
- 0.26.0+ds-2ubuntu2
- 0.26.0+ds-2ubuntu3
- 0.26.0+ds-2ubuntu3+esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published