CVE-2026-20732VulnerabilityPublished 4 Feb 2026

CVE-2026-20732: F5 BIG-IP · User Interface (UI) Misrepresentation of Critical Information

Affects F5 BIG-IPSource CVE Database V5

Not known to be exploited · CVSS 3.1 Low : upgrade to 17.5.1.4 or 17.1.3.1 when convenient.

Data as of 26 Oct 2026, 08:11 UTC

CVSS 3.1 base score

3.1Low

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 17.5.1.4, 17.1.3.1

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade F5 BIG-IP to 17.5.1.4 or 17.1.3.1.

Affected software

Product	Affected	Fixed in
F5BIG-IP	Affected >=17.5.0 <17.5.1.4 >=17.1.0 <17.1.3.1 >=16.1.0	Fixed in 17.5.1.4 17.1.3.1

AI-suggested

1. Monitor administrative interfaces closely for any suspicious or unexpected error messages that could indicate spoofing attempts. 2. Educate network and system administrators to verify error messages through multiple sources before acting on them to avoid misinterpretation. 3. Restrict access to the BIG-IP configuration utility page using network segmentation, VPNs, or IP whitelisting to reduce exposure to unauthenticated attackers. 4. Implement strict input validation and sanitization controls where possible, especially if custom configurations or integrations exist. 5. Regularly check for vendor advisories and apply official patches or updates promptly once released. 6. Employ multi-factor authentication and strong access controls on administrative interfaces to reduce risk of unauthorized access. 7. Use logging and alerting mechanisms to detect unusual UI behavior or repeated error message spoofing attempts. 8. Conduct periodic security assessments and penetration testing focused on UI integrity and administrative interface security. These steps go beyond generic advice by focusing on operational awareness, access restrictions, and proactive detection tailored to this specific UI misrepresentation vulnerability.

Description

A vulnerability exists in an undisclosed BIG-IP Configuration utility page that may allow an attacker to spoof error messages. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Impact

For European organizations, the primary impact is operational rather than direct security compromise. Spoofed error messages in the BIG-IP configuration interface could mislead network administrators, potentially causing misdiagnosis of system health or configuration issues. This may result in delayed response to actual problems or incorrect remediation actions, which could indirectly affect network availability or security posture. Organizations relying heavily on F5 BIG-IP for load balancing, application delivery, or security functions might experience reduced confidence in system alerts. Critical infrastructure sectors, such as finance, telecommunications, and government, that use BIG-IP appliances extensively could face increased risk of operational disruption. However, since the vulnerability does not allow data leakage, privilege escalation, or denial of service, the direct confidentiality, integrity, and availability impacts are minimal. The absence of known exploits and the low CVSS score further reduce immediate risk, but vigilance is necessary to avoid potential exploitation in targeted attacks.

CWE-451User Interface (UI) Misrepresentation of Critical Information (opens in a new tab)
Class weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.
Implementation · Input Validation
Perform data validation (e.g. syntax, length, etc.) before interpreting the data.
Architecture and Design · Output Encoding
Create a strategy for presenting information, and plan for how to display unusual characters.
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
Attack patterns
Spear Phishing (opens in a new tab)
Mobile Phishing (opens in a new tab)
Phishing (opens in a new tab)
Resource Location Spoofing (opens in a new tab)
Action Spoofing (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

my.f5.com/manage/s/article/K000156644 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Feb 2026, 15:30 UTC

WeaknessesCWE-451

Technical details

References

Community reviews

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