CVE-2025-66577Public exploitNetwork attack vector

Client IP spoofing via untrusted forwarding headers

Published Dec 5, 2025 · Updated Dec 5, 2025

Log poisoning in Yuji Hirose cpp-httplib before 0.27.0 allows remote attackers to spoof client IPs through crafted HTTP headers. The get_client_ip() helper in docker/main.cc accepts X-Forwarded-For or X-Real-IP without verifying a trusted proxy and supplies the value to both nginx-style loggers. Any network client that can reach the bundled Docker server can falsify access and error-log attribution, undermining audits and IP-based authorization decisions.

CVSS severity5.3
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Log poisoning in Yuji Hirose cpp-httplib before 0.27.0 allows remote attackers to spoof client IPs through crafted HTTP headers. The get_client_ip() helper in docker/main.cc accepts X-Forwarded-For or X-Real-IP without verifying a trusted proxy and supplies the value to both nginx-style loggers. Any network client that can reach the bundled Docker server can falsify access and error-log attribution, undermining audits and IP-based authorization decisions.

The record

CVE
CVE-2025-66577
Published
Dec 5, 2025
Updated
Dec 5, 2025
Vendor
Yuji Hirose
Product
cpp-httplib
Classifications
CWE-807, CWE-117, T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.27.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Yuji Hirose · cpp-httplibversion=< 0.27.0

Published CVSS scores

5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-807Reliance on Untrusted Inputs in a Security Decision
CWE-117Improper Output Neutralization for Logs
T1565.002Transmitted Data Manipulation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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