cpp-httplib is a C++ header-only HTTP/HTTPS library. From 0.29.0 until 0.51.0, Client::open_stream in httplib.h accepts a caller-controlled path that reaches detail::write_request_line() without the detail::encode_path() protection used by the ordinary buffered request path. Raw carriage-return and line-feed bytes in the path can therefore split the outbound HTTP/1.1 request line and inject attacker-shaped request metadata. Exploitation requires an embedding application to pass remote user input into the open_stream path and a backend or intermediary that interprets the injected bytes; the established impact is modification of backend-visible request data, not direct confidentiality or availability impact. This issue is fixed in version 0.51.0.
History

Sat, 17 Oct 2026 03:30:00 +0000

Type Values Removed Values Added
First Time appeared Yhirose
Yhirose cpp-httplib
Vendors & Products Yhirose
Yhirose cpp-httplib

Wed, 14 Oct 2026 18:45:00 +0000

Type Values Removed Values Added
Description cpp-httplib is a C++ header-only HTTP/HTTPS library. From 0.29.0 until 0.51.0, Client::open_stream in httplib.h accepts a caller-controlled path that reaches detail::write_request_line() without the detail::encode_path() protection used by the ordinary buffered request path. Raw carriage-return and line-feed bytes in the path can therefore split the outbound HTTP/1.1 request line and inject attacker-shaped request metadata. Exploitation requires an embedding application to pass remote user input into the open_stream path and a backend or intermediary that interprets the injected bytes; the established impact is modification of backend-visible request data, not direct confidentiality or availability impact. This issue is fixed in version 0.51.0.
Title cpp-httplib open_stream serializes CRLF in request target into HTTP request line
Weaknesses CWE-113
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-10-14T18:19:38.256Z

Updated: 2026-10-15T15:06:40.241Z

Reserved: 2026-10-01T14:20:19.155Z

Link: CVE-2026-103930

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-14T19:17:07.657

Modified: 2026-10-16T20:04:29.760

Link: CVE-2026-103930

cve-icon Redhat

No data.