VulnerabilityModified
CVE-2026-45372
This vulnerability is fixed in 0.44.0.
CRITICAL 9.9EPSS 0.29%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.29%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 9.9 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L
- EPSS
- 0.29% probability · 22th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-93, CWE-444
- Affected
- yhirose/cpp-httplib
- Source
- security-advisories@github.com
References
- https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4mExploit, Mitigation, Vendor Advisory
- https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4mExploit, Mitigation, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.