CVE-2026-45372
cpp-httplib: HTTP header value percent-decoding in server-side `parse_header` enables CRLF injection
CVSS Score
9.9
EPSS Score
0.0%
EPSS Percentile
13th
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.
| CWE | CWE-93 CWE-444 |
| Vendor | yhirose |
| Product | cpp-httplib |
| Published | May 29, 2026 |
| Last Updated | Jun 1, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
Low
Affected Versions
yhirose / cpp-httplib
< 0.44.0