Cyber Resilience

CVE-2026-34021

High

Published: 15 June 2026

Published
15 June 2026
Modified
17 June 2026
KEV Added
—
Patch
—
CVSS Score v4 8.6 CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0020 9.5th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-34021 is a high-severity Authentication Bypass by Capture-replay (CWE-294) vulnerability in Sec Consult (inferred from references). Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Network Sniffing (T1040); ranked at the 9.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability details

The Wertheim SafeController 5400, Controller 5400 - AssemblyVersion 6.11.8130.22320, uses RS-485 communication between the server and the microcontroller without cryptographic protection. An attacker with access to the communication path between the server and the microcontroller can sniff RS-485 messages and…

more

replay previously observed messages. This can be used, for example, to spoof a "quit alarm" message and continuously deactivate the safe alarm.

CWE(s)
CWE-294

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1040 Network Sniffing Credential Access
Adversaries may passively sniff network traffic to capture information about an environment, including authentication material passed over the network.
attack.mitre.org →
Why these techniques?

Directly enables sniffing and replay of unprotected serial comms (T1040).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Affected Assets

Sec Consult
—
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AC-9 Previous Logon Notification
addresses: CWE-294

Allows detection of capture-replay attacks by showing the replayed logon's timestamp as the last logon.

SC-23 Session Authenticity
addresses: CWE-294

Protects against replay of captured session tokens or credentials by requiring authenticated, fresh session channels.

SC-40 Wireless Link Protection
addresses: CWE-294

Wireless link protections commonly incorporate replay protection, reducing the exploitability of capture-replay weaknesses.

SC-45 System Time Synchronization
addresses: CWE-294

Accurate synchronized time enables tight timestamp windows that directly limit capture-replay windows in authentication protocols.

References