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CVE-2021-31887

27
FAUCET Score

CVE-2021-31887 is a stack-based buffer overflow vulnerability in the FTP server component of various Siemens APOGEE, Desigo, and TALON products, as well as Nucleus NET and Nucleus ReadyStart V3. This flaw, caused by improper validation of the "PWD/XPWD" command length, can lead to Denial-of-Service and Remote Code Execution. With a CVSS score of 8.8 (High), it can be exploited remotely with low attack complexity and authenticated access, potentially impacting confidentiality, integrity, and availability. While there is no evidence of active exploitation or public exploit code, the vulnerability has garnered significant community discussion and media coverage, indicating awareness and potential for future exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:a:siemens:nucleus_net:*:*:*:*:*:*:*:*
< 2017.02.4CPE matchmatch criteria
cpe:2.3:a:siemens:nucleus_readystart_v3:*:*:*:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:a:siemens:nucleus_source_code:*:*:*:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:o:siemens:apogee_modular_building_controller_firmware:*:*:*:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:o:siemens:apogee_modular_equiment_controller_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.37%
Probability of exploitation in next 30 days
EPSS Percentile
82.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0237 is in the 81st percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cert-portal.siemens.com / productcert/pdf/ssa-044112.pdf
Vendor Advisory
cert-portal.siemens.com / productcert/pdf/ssa-114589.pdf
Vendor Advisory