yhirose cpp-httplib up to 0.50.x Request Line Generation httplib.h Client::open_stream path crlf injection

Summaryinfo

A vulnerability labeled as problematic has been found in yhirose cpp-httplib up to 0.50.x. Impacted is the function Client::open_stream of the file httplib.h of the component Request Line Generation. Executing a manipulation of the argument path can lead to crlf injection. The identification of this vulnerability is CVE-2026-103930. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in yhirose cpp-httplib up to 0.50.x and classified as problematic. This vulnerability affects the function Client::open_stream of the file httplib.h of the component Request Line Generation. The manipulation of the argument path with an unknown input leads to a crlf injection vulnerability. The CWE definition for the vulnerability is CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. As an impact it is known to affect integrity. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-103930 since 10/01/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available.

Upgrading to version 0.51.0 eliminates this vulnerability.

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Productinfo

Vendor

• yhirose

Name

• cpp-httplib

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.31
• 0.32
• 0.33
• 0.34
• 0.35
• 0.36
• 0.37
• 0.38
• 0.39
• 0.40
• 0.41
• 0.42
• 0.43
• 0.44
• 0.45
• 0.46
• 0.47
• 0.48
• 0.49
• 0.50

Website

• Product: https://github.com/yhirose/cpp-httplib/

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