CVE-2026-45372
Critical
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.
SeverityCritical
CVSS9.9
Exploit probability—
ProductYhirose Cpp-httplib
PublishedMay 29, 2026
First seenMay 29, 2026
Weakness typeCWE-93CWE-93CWE-444CWE-444
How to fix
Update
- yhirose cpp-httplib0.44.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| yhirose cpp-httplib | v < 0.44.0 | 0.44.0 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
In the Intelligence 360 plan
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.