CVE-2025-46814Network attack vector

IP access-control bypass via unvalidated proxy headers

Published May 6, 2025 · Updated May 6, 2025

Header injection in FastAPI Guard before 2.0.0 allows remote attackers to spoof client IP addresses through X-Forwarded-For. Client-IP extraction accepts attacker-supplied forwarded addresses without verifying that the connection came through a trusted proxy or selecting a validated proxy-chain entry. Exploitation requires an application to rely on the derived address for IP authorization or logging, enabling control bypass, trusted-client impersonation, or false log attribution.

CVSS severity7.5
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Header injection in FastAPI Guard before 2.0.0 allows remote attackers to spoof client IP addresses through X-Forwarded-For. Client-IP extraction accepts attacker-supplied forwarded addresses without verifying that the connection came through a trusted proxy or selecting a validated proxy-chain entry. Exploitation requires an application to rely on the derived address for IP authorization or logging, enabling control bypass, trusted-client impersonation, or false log attribution.

The record

CVE
CVE-2025-46814
Published
May 6, 2025
Updated
May 6, 2025
Vendor
Renzo Franceschini
Product
FastAPI Guard
Classifications
CWE-74, T1036
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2025CVE publishedPublication date reported by the CVE source.
  2. May 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 2.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Renzo Franceschini · FastAPI Guardversion=< 2.0.0

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.4GitHub CNACVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1036Masquerading

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo