Festo SBRD-Q/SBOC-Q/SBOI-Q

1. EXECUTIVE SUMMARY

CVSS v3 8.2
ATTENTION: Exploitable remotely/low attack complexity
Vendor: Festo
Equipment: SBRD-Q/SBOC-Q/SBOI-Q
Vulnerabilities: Incorrect Conversion between Numeric Types, Out-of-bounds Read, Reachable Assertion

2. RISK EVALUATION

Successful exploitation of these vulnerabilities may allow the attacker to read arbitrary data or cause a denial-of-service condition.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Festo reports that the following products are affected:

Festo Firmware installed on Festo Hardware SBOC-Q-R1B: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R1B-S1: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R1C: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R1C-S1: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R2B: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R2B-S1: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R2C: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R3B-WB: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R3B-WB-S1: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R3C-WB: All versions
Festo Firmware installed on Festo Hardware SBOC-Q-R3C-WB-S1: All versions
Festo Firmware installed on Festo Hardware SBOI-Q-R1B: All versions
Festo Firmware installed on Festo Hardware SBOI-Q-R1B-S1: All versions
Festo Firmware installed on Festo Hardware SBOI-Q-R1C: All versions
Festo Firmware installed on Festo Hardware SBOI-Q-R1C-S1: All versions
Festo Firmware installed on Festo Hardware SBOI-Q-R3B-WB: All versions
Festo Firmware installed on Festo Hardware SBOI-Q-R3B-WB-S1: All versions
Festo Firmware installed on Festo Hardware SBOI-Q-R3C-WB: All versions
Festo Firmware installed on Festo Hardware SBOI-Q-R3C-WB-S1: All versions
Festo Firmware installed on Festo Hardware SBRD-Q: All versions

3.2 VULNERABILITY OVERVIEW

3.2.1 INCORRECT CONVERSION BETWEEN NUMERIC TYPES CWE-681

A specifically-crafted packet sent by an attacker to EIPStackGroup OpENer EtherNet/IP commits and versions prior to February 10, 2021, may cause a denial-of-service condition.

CVE-2021-27478 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.2 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H).

3.2.2 OUT-OF-BOUNDS READ CWE-125

A specifically-crafted packet sent by an attacker to EIPStackGroup OpENer EtherNet/IP commits and versions prior to February 10, 2021, may allow an attacker to read arbitrary data.

CVE-2021-27482 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

3.2.3 REACHABLE ASSERTION CWE-617

A specifically-crafted packet sent by an attacker to EIPStackGroup OpENer EtherNet/IP commits and versions prior to February 10, 2021, may result in a denial-of-service condition.

CVE-2021-27500 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.4 REACHABLE ASSERTION CWE-617

A specifically-crafted packet sent by an attacker to EIPStackGroup OpENer EtherNet/IP commits and versions prior to February 10, 2021, may result in a denial-of-service condition.

CVE-2021-27498 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
COUNTRIES/AREAS DEPLOYED: Worldwide
COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

CERT@VDE coordinated these vulnerabilities with Festo.

4. MITIGATIONS

Festo has identified the following specific mitigations and remediations users can apply to reduce risk:

Minimize network exposure for all control system devices and/or systems and ensure that they are not accessible from the Internet.
Deactivate EtherNet/IP in device settings if not used.
There is no fix planned.

For more information, see the associated Festo security advisory FSA-202101 FSA-202101: Festo: Multiple vulnerabilities in Ethernet/IP Stack of SBRD-Q/SBOC-Q/SBOI-Q – HTML, FSA-202101: Festo: Multiple vulnerabilities in Ethernet/IP Stack of SBRD-Q/SBOC-Q/SBOI-Q – CSAF.

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities, such as:

Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
Locate control system networks and remote devices behind firewalls and isolating them from business networks.
When remote access is required, use more secure methods, such as virtual private networks (VPNs). Recognize VPNs may have vulnerabilities, should be updated to the most recent version available, and are only as secure as the connected devices.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.

CISA also recommends users take the following measures to protect themselves from social engineering attacks:

Do not click web links or open attachments in unsolicited email messages.
Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams.
Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks.

No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

September 30, 2025: Initial Republication of Festo FSA-202101

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