CVE-2025-66577
MEDIUMDescription
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 attacker can supply X-Forwarded-For or X-Real-IP headers which get accepted unconditionally by get_client_ip() in docker/main.cc, causing access and error logs (nginx_access_logger / nginx_error_logger) to record spoofed client IPs (log poisoning / audit evasion). This vulnerability is fixed in 0.27.0.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 19% of all known CVEs.
References
Related Vulnerabilities
Other CWE-117 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-43410 | Medium | 5.3 | 2.4% | - | Fix |
| CVE-2022-32549 | Medium | 5.3 | 2.3% | - | - |
| CVE-2019-14864 | Medium | 6.5 | 1.9% | - | Fix |
| CVE-2021-42250 | Medium | 6.5 | 1.8% | - | Fix |
| CVE-2024-47083 | High | 7.5 | 1.6% | - | - |
| CVE-2020-25646 | High | 7.5 | 1.4% | - | - |
Common questions
How do I fix CVE-2025-66577?
Upgrade cpp-httplib on debian unstable to 0.41.0+ds-3 or later.
Is CVE-2025-66577 being actively exploited?
Not that we know of. CVE-2025-66577 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.27% is the estimated probability that it will be exploited in the next 30 days. That is higher than 19% of all scored CVEs.
How severe is CVE-2025-66577?
CVE-2025-66577 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2025-66577 affect?
Published advisories record a fix for cpp-httplib (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-12-11.