CVE-2026-45372

CRITICAL

cpp-httplib: HTTP header value percent-decoding in server-side `parse_header` enables CRLF injection

Title source: cna
STIX 2.1

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.

References (1)

Core 1
Core References

Scores

CVSS v3 9.9
EPSS 0.0004
EPSS Percentile 12.9%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L

Details

CWE
CWE-444 CWE-93
Status published
Products (1)
yhirose/cpp-httplib < 0.44.0
Published May 29, 2026
Tracked Since May 30, 2026