F5 BIG-IP prior 17.1.3.1/17.5.1.4/21.0.0.1 Traffic Management Microkernel infinite loop

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.9$0-$5k0.72

Summaryinfo

A vulnerability was found in F5 BIG-IP. It has been rated as problematic. The impacted element is an unknown function of the component Traffic Management Microkernel. This manipulation causes infinite loop. This vulnerability is handled as CVE-2026-42781. The attack can only be done within the local network. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic was found in F5 BIG-IP. Affected by this vulnerability is an unknown function of the component Traffic Management Microkernel. The manipulation with an unknown input leads to a infinite loop vulnerability. The CWE definition for the vulnerability is CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. As an impact it is known to affect availability. The summary by CVE is:

When embedded Packet Velocity Acceleration (ePVA) acceleration is configured, undisclosed local ethernet traffic can cause an increase in ePVA and Traffic Management Microkernel (TMM) resource utilization.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

The advisory is shared at my.f5.com. This vulnerability is known as CVE-2026-42781 since 05/01/2026. The exploitation appears to be easy. The attack needs to approached within the local network. Neither technical details nor an exploit are publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 316097 (F5 Networks BIG-IP : BIG-IP FastL4 virtual server vulnerability (K000160862)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 17.1.3.1, 17.5.1.4 or 21.0.0.1 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (316097) and CERT Bund (WID-SEC-2026-1532). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • F5 BIG-IP

Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.0
VulDB Meta Temp Score: 4.9

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.5
CNA Vector: 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Infinite loop
CWE: CWE-835 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 316097
Nessus Name: F5 Networks BIG-IP : BIG-IP FastL4 virtual server vulnerability (K000160862)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: BIG-IP 17.1.3.1/17.5.1.4/21.0.0.1

Timelineinfo

05/01/2026 CVE reserved
05/13/2026 +12 days Advisory disclosed
05/13/2026 +0 days VulDB entry created
05/24/2026 +11 days VulDB entry last update

Sourcesinfo

Vendor: f5.com

Advisory: K000160862
Status: Confirmed

CVE: CVE-2026-42781 (🔒)
GCVE (CVE): GCVE-0-2026-42781
GCVE (VulDB): GCVE-100-363601
CERT Bund: WID-SEC-2026-1532 - F5 BIG-IP Produkte: Mehrere Schwachstellen

Entryinfo

Created: 05/13/2026 18:02
Updated: 05/24/2026 23:39
Changes: 05/13/2026 18:02 (76), 05/17/2026 16:33 (7), 05/24/2026 23:39 (2)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Might our Artificial Intelligence support you?

Check our Alexa App!