CVE-2026-45372

FAUCET Score

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.

First published: May 29, 2026Last modified: May 29, 2026

Impacted Technologies

Vendor	Product	Version(s)	CPE
		< 0.44.0CPE matchmatch criteria	cpe:2.3:a:yhirose:cpp-httplib::::::::

CVSS Data

CVSS version used by this source: 3.1

9.9CRITICAL

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 Impact

LOW

Integrity Impact

HIGH

Availability Impact

LOW

Exploitability Score

3.9

Impact Score

5.3

CvssVersion

3.1

Exploit Intelligence

EPSS Score

0.29%

Probability of exploitation in next 30 days

EPSS Percentile

21.7%

Percentile rank of EPSS score among Peer Group

As of 2026-07-27

Model: v2026.06.15

This CVE's current EPSS score of 0.0029 is in the 2nd percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

github_advisoryworkaround availablevia nvd_reference

View patch

References

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

ExploitMitigationVendor Advisory