# CVE-2026-34441: yhirose cpp-httplib HTTP request smuggling in static file handler

Source: https://junglewise.ai/threats/cve-2026-34441-yhirose-cpp-httplib-http-request-smuggling-in-static-file-handler  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-31. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-34441 · Severity: medium · CVSS 4.8 · Published 2026-03-31

cpp-httplib is a popular C++ library used by developers to add web server and client capabilities to their applications. A security flaw in how the library handles web requests allows attackers to "smuggle" hidden commands inside otherwise normal-looking traffic. This could allow an attacker to bypass security filters, access restricted files, or interfere with other users' sessions on the same server.

Technologies: [Yhirose Cpp-Httplib](https://junglewise.ai/threats/technologies/cpp-httplib). Vendors: [Yhirose](https://junglewise.ai/threats/vendors/yhirose).

## Quick answers

**Is CVE-2026-34441 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34441 being exploited in the wild.

**How severe is CVE-2026-34441?** Medium severity, with a CVSS score of 4.8, published 31 March 2026.

**Which products and versions are affected?** Yhirose Cpp-Httplib < 0.40.0.

**Is there a fix for CVE-2026-34441?** A patch was published on 2026-03-28: Version 0.40.0 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-34441 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-34441?** Check whether you run Yhirose Cpp-Httplib at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

cpp-httplib is vulnerable to HTTP Request Smuggling (CWE-444). The root cause is twofold: first, the server's static file handler in `Server::routing()` returns a response for GET/HEAD requests without consuming the request body, leaving unread bytes on the TCP stream that the keep-alive loop interprets as a subsequent request. Second, the library fails to reject requests containing both 'Content-Length' and 'Transfer-Encoding' headers, violating RFC 9112 §6.3. An unauthenticated remote attacker can exploit these behaviors to embed arbitrary HTTP requests within the body of a GET request. This can lead to access control bypass, cache poisoning, or request hijacking. The issue is fixed in version 0.40.0.

## Affected products

- yhirose cpp-httplib < 0.40.0

## Timeline

- 2026-03-28: patched: Version 0.40.0 released
- 2026-03-31: disclosed: GitHub Advisory GHSA-jv63-rm9j-6jwc published
- 2026-03-31: advisory: CVE-2026-34441 published to NVD

## References

- [https://github.com/yhirose/cpp-httplib/releases/tag/v0.40.0](https://github.com/yhirose/cpp-httplib/releases/tag/v0.40.0)
- [https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-jv63-rm9j-6jwc](https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-jv63-rm9j-6jwc)

## Related threats

- [cpp-httplib cookie exposure in cross-origin redirect](https://junglewise.ai/threats/cve-2026-102944-cpp-httplib-is-a-c-header-only-http-https-library-prior-to-0-51)
- [cpp-httplib use-after-free in TLS WebSocket client](https://junglewise.ai/threats/cve-2026-77358-cpp-httplib-use-after-free-in-tls-websocket-client)
- [cpp-httplib CRLF injection in chunked response trailers](https://junglewise.ai/threats/cve-2026-77341-cpp-httplib-crlf-injection-in-chunked-response-trailers)
- [yhirose cpp-httplib denial of service via malformed X-Forwarded-For header](https://junglewise.ai/threats/cve-2026-46527-yhirose-cpp-httplib-denial-of-service-via-malformed-x-forwarded)
- [yhirose cpp-httplib CRLF injection in parse_header](https://junglewise.ai/threats/cve-2026-45372-yhirose-cpp-httplib-crlf-injection-in-parse-header)