CVE-2021-22978Network attack vector

Administrator-session compromise via reflected iControl REST XSS

Published Feb 12, 2021 · Updated Aug 3, 2024

Reflected XSS in F5 BIG-IP 11.6.x through 16.0.x allows remote attackers to compromise the device through an administrator's browser. Undisclosed iControl REST endpoints reflect attacker-controlled request data into responses that execute as script in the victim's browser. Exploitation requires an administrator to open a crafted request, after which the script runs with that session's authority and can completely compromise the appliance.

CVSS severity8.3
High
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 F5 BIG-IP 11.6.x through 16.0.x allows remote attackers to compromise the device through an administrator's browser. Undisclosed iControl REST endpoints reflect attacker-controlled request data into responses that execute as script in the victim's browser. Exploitation requires an administrator to open a crafted request, after which the script runs with that session's authority and can completely compromise the appliance.

The record

CVE
CVE-2021-22978
Published
Feb 12, 2021
Updated
Aug 3, 2024
Vendor
F5 Networks
Product
BIG-IP
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 12, 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=16.0.x before 16.0.1, 15.1.x before 15.1.1, 14.1.x before 14.1.3.1, 13.1.x before 13.1.3.5, and all 12.1.x and 11.6.x versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

F5 Networks · BIG-IPversion=16.0.x before 16.0.1, 15.1.x before 15.1.1, 14.1.x before 14.1.3.1, 13.1.x before 13.1.3.5, and all 12.1.x and 11.6.x versions

Published CVSS scores

8.3NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
5.1NIST NVDAV:N/AC:H/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

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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