VULNERABILITY INTELLIGENCE

CVE-2026-45372

CVSS score9.9 CRITICAL
EPSS probability0.29%
CISA KEVNot currently listed
Published2026-05-29
Last modified2026-07-22
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L

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.

Weakness classification

  • CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')
  • CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Primary references