CVE-2026-21428

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.0, the ``write_headers`` function does not check for CR & LF characters in user supplied headers, allowing untrusted header value to escape header lines. This vulnerability allows attackers to add extra headers, modify request body unexpectedly & trigger an SSRF attack. When combined with a server that supports http1.1 pipelining (springboot, python twisted etc), this can be used for server side request forgery (SSRF). Version 0.30.0 fixes this issue.
Configurations

Configuration 1 (hide)

cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*

History

17 Jun 2026, 10:18

Type Values Removed Values Added
Summary
  • (es) cpp-httplib es una biblioteca HTTP/HTTPS multiplataforma de un solo archivo de cabecera C++11. Antes de la versión 0.30.0, la función 'write_headers' no verifica la presencia de caracteres CR y LF en las cabeceras proporcionadas por el usuario, lo que permite que un valor de cabecera no confiable escape las líneas de cabecera. Esta vulnerabilidad permite a los atacantes añadir cabeceras adicionales, modificar el cuerpo de la solicitud de forma inesperada y desencadenar un ataque SSRF. Cuando se combina con un servidor que soporta el pipelining de http1.1 (springboot, python twisted, etc.), esto puede utilizarse para la falsificación de solicitudes del lado del servidor (SSRF). La versión 0.30.0 corrige este problema.

06 Jan 2026, 18:20

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 7.5
CPE cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*
First Time Yhirose cpp-httplib
Yhirose
References () https://github.com/yhirose/cpp-httplib/commit/98048a033a532ff22320ce1d11789f8d5710dfcd - () https://github.com/yhirose/cpp-httplib/commit/98048a033a532ff22320ce1d11789f8d5710dfcd - Patch
References () https://github.com/yhirose/cpp-httplib/releases/tag/v0.30.0 - () https://github.com/yhirose/cpp-httplib/releases/tag/v0.30.0 - Product, Release Notes
References () https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-wpc6-j37r-jcx7 - () https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-wpc6-j37r-jcx7 - Exploit, Third Party Advisory

01 Jan 2026, 18:15

Type Values Removed Values Added
New CVE

Information

Published : 2026-01-01 18:15

Updated : 2026-06-17 10:18


NVD link : CVE-2026-21428

Mitre link : CVE-2026-21428

CVE.ORG link : CVE-2026-21428


JSON object : View

Products Affected

yhirose

  • cpp-httplib
CWE
CWE-93

Improper Neutralization of CRLF Sequences ('CRLF Injection')