F5 BIG-IP prior 17.1.3.1/17.5.1.4/21.0.0.1 Traffic Management Microkernel use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.3$5k-$25k0.00

Summaryinfo

A vulnerability marked as critical has been reported in F5 BIG-IP. This affects an unknown part of the component Traffic Management Microkernel. The manipulation leads to use after free. This vulnerability is listed as CVE-2026-41218. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in F5 BIG-IP. It has been rated as critical. This issue affects an unknown code of the component Traffic Management Microkernel. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is availability. The summary by CVE is:

When BIG-IP PEM iRules are configured on a virtual server (iRules using commands starting with CLASSIFICATION::, CLASSIFY::, PEM::, PSC::, and the urlcatquery command), undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

It is possible to read the advisory at my.f5.com. The identification of this vulnerability is CVE-2026-41218 since 05/01/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 05/24/2026).

The vulnerability scanner Nessus provides a plugin with the ID 316105 (F5 Networks BIG-IP : BIG-IP PEM iRules vulnerability (K000160875)), 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 (316105) and CERT Bund (WID-SEC-2026-1532). Statistical analysis made it clear that VulDB provides the best quality for 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: 7.5
VulDB Meta Temp Score: 7.3

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 316105
Nessus Name: F5 Networks BIG-IP : BIG-IP PEM iRules vulnerability (K000160875)

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: K000160875
Status: Confirmed

CVE: CVE-2026-41218 (🔒)
GCVE (CVE): GCVE-0-2026-41218
GCVE (VulDB): GCVE-100-363563
CERT Bund: WID-SEC-2026-1532 - F5 BIG-IP Produkte: Mehrere Schwachstellen

Entryinfo

Created: 05/13/2026 17:43
Updated: 05/24/2026 23:29
Changes: 05/13/2026 17:43 (76), 05/17/2026 14:43 (7), 05/24/2026 23:29 (2)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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