CVE-2026-34441: CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') in yhirose cpp-httplib
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.
AI Analysis
Technical Summary
cpp-httplib, a C++11 single-file header-only HTTP/HTTPS library, had a vulnerability (CWE-444) in versions before 0.40.0 where the static file handler served GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, leftover unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. This allows an attacker to smuggle an arbitrary HTTP request embedded inside the body of a GET request, which the server then processes as a separate request. The issue is addressed in version 0.40.0.
Potential Impact
The vulnerability allows an attacker to perform HTTP Request Smuggling, potentially enabling them to bypass security controls or interfere with request processing by injecting crafted HTTP requests. The CVSS score of 4.8 indicates a medium severity with low confidentiality and integrity impact and no availability impact. There are no known exploits in the wild.
Mitigation Recommendations
This vulnerability has been patched in cpp-httplib version 0.40.0. Users should upgrade to version 0.40.0 or later to remediate this issue. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-34441: CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') in yhirose cpp-httplib
Description
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
cpp-httplib, a C++11 single-file header-only HTTP/HTTPS library, had a vulnerability (CWE-444) in versions before 0.40.0 where the static file handler served GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, leftover unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. This allows an attacker to smuggle an arbitrary HTTP request embedded inside the body of a GET request, which the server then processes as a separate request. The issue is addressed in version 0.40.0.
Potential Impact
The vulnerability allows an attacker to perform HTTP Request Smuggling, potentially enabling them to bypass security controls or interfere with request processing by injecting crafted HTTP requests. The CVSS score of 4.8 indicates a medium severity with low confidentiality and integrity impact and no availability impact. There are no known exploits in the wild.
Mitigation Recommendations
This vulnerability has been patched in cpp-httplib version 0.40.0. Users should upgrade to version 0.40.0 or later to remediate this issue. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-27T18:18:14.894Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 69cc3ec9e6bfc5ba1d43daaf
Added to database: 3/31/2026, 9:38:17 PM
Last enriched: 4/8/2026, 2:04:43 AM
Last updated: 5/15/2026, 3:56:06 PM
Views: 55
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