What is CVE-2025-66577?

CVE-2025-66577 is a medium-severity vulnerability in Yhirose Cpp-httplib, classified under Improper Output Neutralization for Logs. CVSS score: 5.3/10. Published 2025-12-05.

How severe is CVE-2025-66577?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Yhirose Cpp-httplib

CVE-2025-66577

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.27.0, a vulnerability allows attacker-controlled HTTP headers to influence server-visible metadata, logging, and authorization decisions. An attac…

EPSS: 0.001 (16.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

Affected products

Yhirose Cpp-httplib — versions < 0.27.0

Weakness classification (CWE)

References

https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-gfpf-r66f-5mh2 (x_refsource_CONFIRM)
https://github.com/yhirose/cpp-httplib/commit/ac9ebb0ee333ce8bf13523f487bdfad9518a2aff (x_refsource_MISC)

Frequently asked questions

What is CVE-2025-66577?: CVE-2025-66577 is a medium-severity vulnerability in Yhirose Cpp-httplib, classified under Improper Output Neutralization for Logs. CVSS score: 5.3/10. Published 2025-12-05.
How severe is CVE-2025-66577?: Medium severity. CVSS v3 base score is 5.3 out of 10.