CVE-2021-23037Network attack vector

Session-context script execution via undisclosed page

Published Sep 14, 2021 · Updated Aug 3, 2024

Reflected XSS in the F5 BIG-IP Configuration utility allows remote attackers to execute JavaScript in a logged-in user's context. F5 has not disclosed the affected page or the input reflected without output neutralization, so the request parameter and rendering path remain unknown. All evaluated 11.6.x, 12.1.x, 13.1.x, 14.1.x, 15.1.x, 16.0.x, and 16.1.x releases are affected, and exploitation requires user interaction in an authenticated utility session.

CVSS severity9.6
Critical
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in the F5 BIG-IP Configuration utility allows remote attackers to execute JavaScript in a logged-in user's context. F5 has not disclosed the affected page or the input reflected without output neutralization, so the request parameter and rendering path remain unknown. All evaluated 11.6.x, 12.1.x, 13.1.x, 14.1.x, 15.1.x, 16.0.x, and 16.1.x releases are affected, and exploitation requires user interaction in an authenticated utility session.

The record

CVE
CVE-2021-23037
Published
Sep 14, 2021
Updated
Aug 3, 2024
Vendor
F5 Networks
Product
BIG-IP
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 14, 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=All versions of 16.1.x, 16.0.x, 15.1.x, 14.1.x, 13.1.x, 12.1.x, and 11.6.x

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

F5 Networks · BIG-IPversion=All versions of 16.1.x, 16.0.x, 15.1.x, 14.1.x, 13.1.x, 12.1.x, and 11.6.x

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
9.6NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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