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 (isfieldvalue) 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.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-444",
"CWE-93"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45372.json"
}{
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "0.44.0"
}
],
"source": [
"AFFECTED_FIELD",
"CPE_RANGE"
],
"cpe": "cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*"
}