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F5 BIG-IP EUVDEUVD-2026-30002

| CVE-2026-42781 HIGH
Loop with Unreachable Exit Condition (Infinite Loop) (CWE-835)
2026-05-13 f5 GHSA-543h-qfcx-5xww
7.1
CVSS 4.0 · Vendor: f5
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Recon
    Attacker gains local network access
  2. Delivery
    Crafts malformed ethernet frames
  3. Exploit
    Sends frames to BIG-IP ePVA processor
  4. Install
    ePVA enters unbounded loop or excessive resource allocation
  5. C2
    TMM resources exhausted
  6. Execute
    BIG-IP becomes unresponsive
  7. Impact
    Denial of service to downstream applications

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Loop termination conditions
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Embedded Packet Velocity Acceleration (ePVA) must be explicitly enabled in BIG-IP configuration - this is not a default feature. Attacker must have adjacent network access (AV:A): direct connection to the same ethernet segment, VLAN, or local network as the BIG-IP management or data plane. No authentication, special privileges, or user interaction required. Exploitation is feasible only in network topologies where untrusted or compromised internal hosts can reach the BIG-IP; air-gapped or DMZ-segmented deployments significantly reduce practical risk.

Impact

CVSS vector (AV:A/AC:L/PR:N/UI:N/S:U) indicates adjacent network attack vector with low complexity and no privileges or user interaction required - realistically limited to local network segments. EPSS score unavailable, preventing probabilistic exploitation assessment. KEV status not provided; no public POC identified at time of analysis. Real-world risk depends critically on network topology: denial of service via ePVA exhaustion is severe only if the target environment relies on BIG-IP for critical load balancing or traffic management and the attacker has local network access (VLAN, same subnet, or direct connection). The 'undisclosed' nature of the triggering traffic suggests the vendor has not published technical details, limiting independent verification. High-availability systems with redundant BIG-IP instances and local network segmentation constraints reduce practical impact.

Exploit ScenarioDerived

An attacker with adjacent network access (same L2 segment or VLAN as BIG-IP) sends a sequence of specially-crafted ethernet frames targeting the ePVA subsystem. These frames trigger unbounded resource allocation or iteration in ePVA and TMM, exhausting CPU, memory, or internal buffers. Within seconds to minutes, BIG-IP becomes unresponsive to legitimate traffic, causing service disruption for applications depending on the load balancer.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – May 13, 2026

Denial of service in F5 BIG-IP when Packet Velocity Acceleration (ePVA) is enabled allows local network attackers to exhaust ePVA and Traffic Management Microkernel (TMM) resources through crafted ethernet traffic, causing service degradation or unavailability. CVSS 6.5 (medium severity) reflects adjacent network access requirement and high availability impact. Patch availability confirmed via vendor advisory.

RemediationAI

Apply vendor-released patch from F5 article K000160862 (https://my.f5.com/manage/s/article/K000160862). Exact patched versions not specified in provided data; consult F5 advisory for your BIG-IP version and ePVA configuration. As immediate compensating control, disable ePVA acceleration if acceptable for performance SLAs, or restrict local network access to trusted management and traffic source segments using network ACLs or VLAN isolation. Note: Disabling ePVA trades acceleration performance for availability; evaluate impact on throughput SLAs before implementing.

Affected VersionsENISA

BIG-IP 17.5.0 <17.5.1.4
BIG-IP 17.1.0 <17.1.3.1
BIG-IP 21.0.0 <21.0.0.1

Affected Packages

euvd big_ip fix: 17.1.3.1, 17.5.1.4, 21.0.0.1

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

F5 BIG-IP implements embedded Packet Velocity Acceleration (ePVA) as a hardware acceleration feature to optimize traffic processing. The Traffic Management Microkernel (TMM) manages resource allocation for network traffic. The vulnerability exploits improper resource handling in the ePVA subsystem when processing locally-reachable ethernet frames; CWE-835 (infinite loop) indicates the root cause is likely unbounded iteration or resource consumption triggered by malformed or specifically-crafted local network packets. This affects systems where ePVA acceleration is explicitly configured as an enabled feature, not default deployments.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (f5) PRIMARY 7.1 HIGH
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (f5) · only source for this CVE.

CVSS VectorVendor: f5

Attack Vector
Adjacent
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

3
Severity Changed
May 13, 2026 - 16:22 NVD
MEDIUM HIGH
CVSS changed
May 13, 2026 - 16:22 NVD
6.5 (MEDIUM) 7.1 (HIGH)
CVE Published
May 13, 2026 - 14:12 nvd
MEDIUM 6.5

DescriptionCVE.org

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.

Threat Intelligence Overview

EPSS Score
0.0%
Top 94% exploitable
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Controlled
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

36
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +36
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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