Is CVE-2025-66577 in the CISA KEV catalog?

No. CVE-2025-66577 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-66577?

CVE-2025-66577 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2025-66577?

CVE-2025-66577 has an EPSS score of 0.24% (14th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-66577?

Upgrade cpp-httplib on debian unstable to 0.41.0+ds-3 or later.

CVE & CISA-KEV Catalog

CVE-2025-66577

MEDIUM

5.3

CVSS v3

NVD

Description

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.

CWE-117 CWE-807

How to fix

Remediation Available

cpp-httplibDebian

Fixed in:0.41.0+ds-3CVE-2025-66577

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

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Exploit Intelligence

0.24%probability of exploitation in 30 days

14thpercentile

Low risk: more likely to be exploited than 14% of all known CVEs.

References

Patch1

github.com

Exploit1

github.com

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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.