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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.

PUBLISHED Reserved 2026-05-12 | Published 2026-05-29 | Updated 2026-06-01 | Assigner GitHub_M




CRITICAL: 9.9CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L

Problem types

CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')

CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Product status

< 0.44.0
affected

References

github.com/...ttplib/security/advisories/GHSA-xjxg-64p4-vj4m exploit

github.com/...ttplib/security/advisories/GHSA-xjxg-64p4-vj4m

cve.org (CVE-2026-45372)

nvd.nist.gov (CVE-2026-45372)

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