CVE-2021-23007Network attack vector

Fragmented-IP service interruption via TMM traffic handling

Published Mar 31, 2021 · Updated Aug 3, 2024

Denial of service in F5 BIG-IP 14.1.4 and 16.0.1.1 allows remote attackers to interrupt fragmented IP traffic via network traffic. TMM handles certain undisclosed traffic incorrectly and then drops all fragmented IP traffic; F5 has not disclosed the triggering pattern. The trigger needs network reachability but no authentication or user interaction, and the documented effect is traffic loss rather than a TMM crash.

CVSS severity5.3
Medium
EPSS probability1.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in F5 BIG-IP 14.1.4 and 16.0.1.1 allows remote attackers to interrupt fragmented IP traffic via network traffic. TMM handles certain undisclosed traffic incorrectly and then drops all fragmented IP traffic; F5 has not disclosed the triggering pattern. The trigger needs network reachability but no authentication or user interaction, and the documented effect is traffic loss rather than a TMM crash.

The record

CVE
CVE-2021-23007
Published
Mar 31, 2021
Updated
Aug 3, 2024
Vendor
F5 Networks
Product
BIG-IP
Classifications
T1498
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 31, 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

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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=14.1.4 and 16.0.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

F5 Networks · BIG-IPversion=14.1.4 and 16.0.1.1

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
5.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.3F5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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

T1498Network Denial of Service

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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