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CVE-2021-27393

MEDIUM
5.3
CVSS Score
Published: April 22, 2021 at 08:42 PM UTC
Updated: June 17, 2026 at 03:44 AM UTC
3 products affected across 1 vendorNucleus NETNucleus ReadyStart V3Nucleus Source Code

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.8%

Description

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

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Nucleus NET· Siemens
95%
All versions
Nucleus ReadyStart V3· Siemens
95%
v < 2013.08All versions < V2013.08
Affected range stops below 2013.08, so it looks safe — our inference, not a vendor statement
Nucleus Source Code· Siemens
60%
Versions including affected DNS modules

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

x_refsource_MISCVendor Advisory
Source: [email protected]
https://cert-portal.siemens.com/productcert/pdf/ssa-201384.pdf

CVSS

5.3MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-330

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