---
id: CVE-2026-34441
title: >-
  cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS
  library
summary: >-
  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 r…
severity: medium
cvss: 4.8
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-444
vendor: yhirose
product: cpp-httplib
affected:
  - cpp-httplib < 0.40.0
patched:
  - cpp-httplib 0.40.0
published: '2026-03-31'
updated: '2026-07-24'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-34441'
references:
  - url: 'https://github.com/yhirose/cpp-httplib/releases/tag/v0.40.0'
    label: security-advisories@github.com
  - url: >-
      https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-jv63-rm9j-6jwc
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00279
epssPercentile: 0.18151
ingestedAt: '2026-07-25T21:03:57.929Z'
---

## Overview

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.

## Affected

- `cpp-httplib < 0.40.0`

## Remediation

Upgrade past the affected range:

- `cpp-httplib 0.40.0`