Security readout for executives and security teams
Plain-English summary
Some Siemens RUGGEDCOM industrial networking devices can mishandle DHCP packets, causing memory overwrite and possible remote code execution. This matters because these devices often sit in operational networks where compromise can affect availability and trusted network paths. The issue is high severity, but the CVSS vector marks attack complexity as high.
Executive priority
Treat this as a high-priority OT network hygiene issue. It is not marked as actively exploited in the provided evidence, but the potential impact includes remote code execution on industrial networking equipment, making exposed legacy firmware unacceptable in critical environments.
Technical view
CVE-2021-31895 is a CWE-120 buffer-style memory overwrite in the DHCP client of affected Siemens RUGGEDCOM devices. An unauthenticated remote attacker able to deliver malicious DHCP packets to the device could potentially achieve remote code execution. Affected versions are below V4.3.7 or V5.5.4 depending on model family.
Likely exposure
Exposure is most likely in Siemens RUGGEDCOM deployments listed by the advisory that run affected firmware and use DHCP client behavior. RUGGEDCOM fleets in OT, utility, transportation, or industrial networks should be prioritized for firmware inventory and network reachability review.
Exploitation context
The provided bundle does not show CISA KEV listing or active exploitation. The CVSS vector is network-accessible, unauthenticated, no user interaction, high impact, and high attack complexity. The source indicates Siemens has official remediation available.
Researcher notes
Focus validation on the DHCP client attack surface, exact firmware branch, and model-specific fixed version. Avoid assuming all RUGGEDCOM products are affected; use the Siemens advisory list. Evidence provided supports potential RCE, not confirmed active exploitation.
Mitigation direction
- Identify listed RUGGEDCOM models and firmware versions in asset inventory.
- Upgrade affected V4.x devices to V4.3.7 or later where applicable.
- Upgrade affected V5.x devices to V5.5.4 or later where applicable.
- Restrict untrusted network paths to device management and DHCP-related traffic.
- Check Siemens SSA-373591 for model-specific guidance before changes.
Validation and detection
- Confirm each RUGGEDCOM model and firmware version against Siemens SSA-373591.
- Verify whether devices are below V4.3.7 or V5.5.4 thresholds.
- Review network segmentation around affected industrial devices.
- Confirm remediation completion through firmware inventory evidence.
- Monitor vendor advisories for updates to Siemens guidance.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-120: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-31895 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C2.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://cert-portal.siemens.com/productcert/pdf/ssa-373591.pdfCVE reference · x_refsource_MISC
- https://cert-portal.siemens.com/productcert/html/ssa-373591.htmlCVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.