Cyber Resilience

CVE-2021-27393

Medium

Published: 22 April 2021

Published
22 April 2021
Modified
21 November 2024
KEV Added
Patch
CVSS Score v3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS Score 0.0022 44.4th percentile
Risk Priority 11 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-27393 is a medium-severity Use of Insufficiently Random Values (CWE-330) vulnerability in Siemens Nucleus Net. Its CVSS base score is 5.3 (Medium).

Operationally, ranked at the 44.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

A vulnerability has been identified in Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2013.08), Nucleus Source Code (Versions including affected DNS modules). The DNS client does not properly randomize UDP port numbers of DNS requests. That could…

more

allow an attacker to poison the DNS cache or spoof DNS resolving.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

siemens
nucleus net
all versions
siemens
nucleus readystart v3
≤ 2013.08
siemens
nucleus source code
all versions

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.

addresses: CWE-330

Key generation under controlled management uses approved random-bit sources rather than insufficiently random values.

References