Vitogate 300: Client-Side Enforcement of Server-Side Security
CVE-2025-9495 is a high-severity client-side enforcement of server-side security vulnerability in Vitogate 300 from Viessmann, with a CVSS 4.0 base score of 8.7 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists version 3.0.0.0 as the first without the flaw, so updating Vitogate 300 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.24% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Vitogate 300 to 3.0.0.0 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Viessmann | Vitogate 300 | 1 up to, but not including, 3.0.0.0 | 3.0.0.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Attack requirements
- NoneThe attack does not depend on a particular deployment or configuration.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA (carrier.com).
Official description
The Vitogate 300 web interface fails to enforce proper server-side authentication and relies on frontend-based authentication controls. This allows an attacker to simply modify HTML elements in the browser’s developer tools to bypass login restrictions. By removing specific UI elements, an attacker can reveal the hidden administration menu, giving them full control over the device.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Client-Side Enforcement of Server-Side Security
The product includes a server that relies on the client to implement a protection mechanism that is intended to protect the server.
How developers prevent this class of flaw
- If some degree of trust is required between the two entities, then use integrity checking and strong authentication to ensure that the inputs are coming from a trusted source. Design the product so that this trust is managed in a centralized fashion, especially if there are complex or numerous communication channels, in order to reduce the risks that the implementer will mistakenly omit a check in a single code path.
More Client-Side Enforcement of Server-Side Security vulnerabilities (CWE-602)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Vitogate 300
- 8.5 High severity
- 9.8 Critical severity
Recent Client-Side Enforcement of Server-Side Security vulnerabilities
- 8.8 High severity
- 7.5 High severity
- 7.7 High severity
- 7.5 High severity
- 8.8 High severity
- 7.1 High severity
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