CVE-2026-45372

Summary

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.

Affected Software

Weaknesses

• CWE-93: CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')
• CWE-444: CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: yes
  • Technical Impact: partial

Additional References

• https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4m

References

• https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4m

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