← Vulnerability feed

Vulnerability record · CVE-2026-45372 · published 29 May 2026

CVE-2026-45372: Yhirose cpp-httplib http request smuggling vulnerability

YYhirose · Cpp Httplib

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's server parses an incoming request, it applies percent-decoding to every header value except Location and Referer. The validity check (is_field_value) is run before decoding, so encoded %0D%0A passes the check and is then expanded to a literal \r\n byte pair inside the stored header value. This vulnerability is fixed in 0.44.0.

9.9 CVSS 3.1 Critical EPSS 0.41% · top 67.3% CWE-93 · CWE-93CWE-444 · HTTP request smuggling
9.9CVSS 3.1 base score
0.41%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
22 Jul 2026Last modified by NVD

Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's server parses an incoming request, it applies percent-decoding to every header value except Location and Referer. The validity check (is_field_value) is run before decoding, so encoded %0D%0A passes the check and is then expanded to a literal \r\n byte pair inside the stored header value. This vulnerability is fixed in 0.44.0.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4m ExploitMitigationVendor Advisory
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4m ExploitMitigationVendor Advisory

Track CVE-2026-45372 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2025-66570Yhirose cpp-httplib authentication bypass by spoofing vulnerabilitycpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.27.0, a vulnerability allows attacker-controlled HTTP he…EPSS 0.33%8.7CVE-2026-46527Yhirose cpp-httplib null pointer dereference vulnerabilitycpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_pro…EPSS 0.49%8.7CVE-2026-22776Yhirose cpp-httplib vulnerabilitycpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.1, a Denial of Service (DoS) vulnerability ex…EPSS 0.40%8.1CVE-2026-32627Yhirose cpp-httplib improper certificate validation vulnerabilitycpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.37.2, when a cpp-httplib client is configured with a pro…EPSS 0.25%7.7CVE-2026-21428Yhirose cpp-httplib vulnerabilitycpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.0, the ``write_headers`` function does not ch…EPSS 0.41%7.5CVE-2026-45352Yhirose cpp-httplib improper input validation vulnerabilitycpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.43.4, negative chunk-size in chunked Transfer-Encoding c…EPSS 0.49%7.5CVE-2026-31870Yhirose cpp-httplib vulnerabilitycpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.37.1, when a cpp-httplib client uses the streaming API (…EPSS 0.55%7.5CVE-2026-28435Yhirose cpp-httplib uncontrolled resource consumption vulnerabilitycpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.35.0, cpp-httplib (httplib.h) does not enforce Server::s…EPSS 0.60%

Source: NIST National Vulnerability Database (record CVE-2026-45372), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.