VulnerabilityPublished 9 Mar 2026

CVE-2025-41760: MBS UBR-01 Mk II · Failing Open

Affects MBS UBR-01 Mk IISource CVE Database V5

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Not known to be exploited · CVSS 4.9 Medium : upgrade to 6.0.1.0 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

4.9Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 6.0.1.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: High
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade UBR-01 Mk II and UBR-02 and UBR-LON to 6.0.1.0.

Affected software

Product	Affected	Fixed in
MBSUBR-01 Mk II	Affected <6.0.1.0	Fixed in 6.0.1.0
MBSUBR-02	Affected <6.0.1.0	Fixed in 6.0.1.0
MBSUBR-LON	Affected <6.0.1.0	Fixed in 6.0.1.0

AI-suggested

Avoid configuring pass filters with empty tables on the MBS UBR-01 Mk II device to prevent the fail-open condition.
Implement strict change management and configuration review processes to detect and prevent misconfigurations involving empty filter lists.
Monitor network traffic for unexpected or unauthorized flows that could indicate filter bypass.
Segregate administrative access to the device to trusted personnel only, minimizing the risk of accidental or malicious misconfiguration.
Engage with the vendor MBS to obtain firmware updates or patches addressing this vulnerability once released.
Consider deploying additional network security controls such as intrusion detection/prevention systems (IDS/IPS) or next-generation firewalls to provide layered defense in case of filter failure.
Conduct regular security audits and penetration testing focused on network filtering rules and device configurations to identify similar fail-open conditions.
Document and train network administrators on the correct use of filtering configurations and the risks associated with empty filter lists.

Description

An administrator may attempt to block all traffic by configuring a pass filter with an empty table. However, in UBR, an empty list does not enforce any restrictions and allows all network traffic to pass unfiltered.

Impact

The primary impact of CVE-2025-41760 is the potential exposure of sensitive network traffic due to the device allowing all traffic when an empty pass filter is configured. This undermines confidentiality protections and could facilitate data leakage or unauthorized access to internal network segments. Organizations using the MBS UBR-01 Mk II as a security boundary or traffic filter may inadvertently allow malicious or unauthorized traffic if the empty filter misconfiguration occurs. While the vulnerability does not affect integrity or availability directly, the loss of confidentiality can have serious consequences, including data breaches, compliance violations, and increased risk of lateral movement by attackers. The requirement for administrative privileges to configure the filter limits exploitation to insiders or attackers who have already gained elevated access. However, the ease of misconfiguration and lack of fail-secure behavior increase the risk of accidental exposure. Given the device’s role in network traffic filtering, critical infrastructure, government, and enterprises relying on this product could face significant risks if this vulnerability is not addressed.

CWE-636Not Failing Securely (Failing Open) (opens in a new tab)
Class weaknessOWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions.
Architecture and Design
Subdivide and allocate resources and components so that a failure in one part does not affect the entire product.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

mbs-solutions.de/mbs-2025-0001 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Mar 2026, 09:41 UTC

WeaknessesCWE-636

Technical details

References

Community reviews

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