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Fencer Vulns
medium 6.5

CVE-2020-27737 json

A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions…

published 2021-04-22 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-20241

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.6%
EPSS 3.6% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.3), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions < V0.5.0.0), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS response parsing functionality does not properly validate various length and counts of the records. The parsing of malformed responses could result in a read past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition or leak the memory past the allocated structure.

Patch / fix

  • siemens nucleus_readystart_v3 2017.02.3
  • siemens nucleus_readystart_v4 4.1.0
  • siemens simotics_connect_400_firmware 0.5.0.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-21-103-13 updated cvss 6.5

Siemens SIMOTICS CONNECT 400 (Update A)

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-22-349-16 updated cvss 6.5

Siemens APOGEE and TALON

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

3.57% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H/E:P/RL:O/RC:C
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:P/I:N/A:P

Affected products

  • Siemens APOGEE PXC Compact (BACnet)
  • Siemens APOGEE PXC Compact (P2 Ethernet)
  • Siemens APOGEE PXC Modular (BACnet)
  • Siemens APOGEE PXC Modular (P2 Ethernet)
  • Siemens Nucleus NET
  • Siemens Nucleus ReadyStart V3
  • Siemens Nucleus ReadyStart V4
  • Siemens Nucleus Source Code
  • Siemens SIMOTICS CONNECT 400
  • Siemens TALON TC Compact (BACnet)
  • Siemens TALON TC Modular (BACnet)

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.