CVE-2026-45372
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.
Scoring
- Severity
- CRITICAL
- CVSS base score
- 9.9
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L
- EPSS probability
- 0.29%
- CWE
- CWE-93, CWE-444
- Published
- 2026-05-29
- Last modified
- 2026-06-01
Affected products
- yhirose cpp-httplib
Weakness type
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