cpp-httplib: HTTP Request Smuggling via Unconsumed GET Request Body

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Summary

CVECVE-2026-34441
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-31 22:16:19 UTC
Updated2026-04-01 20:28:01 UTC
Descriptioncpp-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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS: 0.000280000 probability, percentile 0.076440000 (date 2026-04-01)

Problem Types: CWE-444 | CWE-444 CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
3.1[email protected]Secondary4.8MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
3.1CNADECLARED4.8MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Yhirose Cpp-httplib All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Yhirose Cpp-httplib affected < 0.40.0 Not specified

References

ReferenceSourceLinkTags
github.com/yhirose/cpp-httplib/releases/tag/v0.40.0 [email protected] github.com Product, Release Notes
github.com/yhirose/cpp-httplib/security/advisories/GHSA-jv63-rm9j-6jwc [email protected] github.com Exploit, Mitigation, Vendor Advisory
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