CVE-2023-36456Network attack vector

IP spoofing via untrusted proxy headers

Published Jul 6, 2023 · Updated Nov 14, 2024

Improper proxy-header validation in authentik 2023.4.2 and earlier and 2023.5.0 through 2023.5.4 allows remote attackers to spoof client IPs. The Go HTTP middleware accepted X-Forwarded-For from any peer, and Python then treated the supplied value as the client address. Exposure requires direct user access without a reverse proxy; forged addresses can taint logs, bypass IP-based flow policy, or reach proxied applications.

CVSS severity8.3
High
EPSS probability0.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper proxy-header validation in authentik 2023.4.2 and earlier and 2023.5.0 through 2023.5.4 allows remote attackers to spoof client IPs. The Go HTTP middleware accepted X-Forwarded-For from any peer, and Python then treated the supplied value as the client address. Exposure requires direct user access without a reverse proxy; forged addresses can taint logs, bypass IP-based flow policy, or reach proxied applications.

The record

CVE
CVE-2023-36456
Published
Jul 6, 2023
Updated
Nov 14, 2024
Vendor
Authentik Security Inc.
Product
authentik
Classifications
CWE-436, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 14, 2024Record 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=< 2023.4.3
  2. Affected versionversion=>= 2023.5.0, < 2023.5.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Authentik Security Inc. · authentikversion=< 2023.4.3; version=>= 2023.5.0, < 2023.5.5

Published CVSS scores

8.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
7.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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-436Interpretation Conflict
T1190Exploit Public-Facing Application

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

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Your stack

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