CVE-2021-23008Public exploitNetwork attack vector

Unauthenticated access via unvalidated Kerberos AS-REP

Published May 10, 2021 · Updated Aug 3, 2024

Authentication bypass in F5 BIG-IP Access Policy Manager affected releases allows remote attackers to access protected applications without valid credentials. APM grants access after a successful Kerberos AS-REP without requesting and validating a service ticket against a trusted KDC key. Exploitation requires hijacking the KDC connection or controlling the Active Directory server, and it exposes applications protected by the affected access policy.

CVSS severity9.8
Critical
EPSS probability1.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in F5 BIG-IP Access Policy Manager affected releases allows remote attackers to access protected applications without valid credentials. APM grants access after a successful Kerberos AS-REP without requesting and validating a service ticket against a trusted KDC key. Exploitation requires hijacking the KDC connection or controlling the Active Directory server, and it exposes applications protected by the affected access policy.

The record

CVE
CVE-2021-23008
Published
May 10, 2021
Updated
Aug 3, 2024
Vendor
F5 Networks
Product
BIG-IP Access Policy Manager
Classifications
CWE-287, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=15.1.x before 15.1.3, 14.1.x before 14.1.4, 13.1.x before 13.1.4, 12.1.x before 12.1.6, and all versions of 16.0.x and 11.6.x.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

F5 Networks · BIG-IP Access Policy Managerversion=15.1.x before 15.1.3, 14.1.x before 14.1.4, 13.1.x before 13.1.4, 12.1.x before 12.1.6, and all versions of 16.0.x and 11.6.x.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-287Improper Authentication
T1557Adversary-in-the-Middle

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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