Quick answers
- Is CVE-2026-42781 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-42781 being exploited in the wild.
- How severe is CVE-2026-42781?
- Medium severity, with a CVSS score of 6.5, published 13 May 2026.
- Which products and versions are affected?
- F5 BIG-IP 17.1.0 to 17.1.3.1, 17.5.0 to 17.5.1.4, 21.0.0 to 21.0.0.1, Undisclosed versions (excluding EoTS).
- Is there a fix for CVE-2026-42781?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-42781 attacked?
- It is attacked from the adjacent network, in a network appliance.
- Am I affected by CVE-2026-42781?
- Check whether you run F5 BIG-IP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A resource exhaustion vulnerability exists in F5 BIG-IP systems when embedded Packet Velocity Acceleration (ePVA) is configured. The flaw is triggered by undisclosed local ethernet traffic, which causes an infinite loop (CWE-835) or similar condition leading to increased resource utilization in both the ePVA hardware and the Traffic Management Microkernel (TMM). An attacker on the adjacent network can exploit this to cause a denial-of-service (DoS) condition. The issue affects multiple BIG-IP modules across rSeries and VELOS platforms. Patches are available in updated versions (e.g., 17.1.3.1, 17.5.1.4, and 21.1.0).
Affected products
- F5 BIG-IP 17.1.0 to 17.1.3.1, 17.5.0 to 17.5.1.4, 21.0.0 to 21.0.0.1
Timeline
- 2026-05-13: advisory: Initial advisory published by F5