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Industrial control advisorySeverity 8.3 high
Wärtsilä FOS-Onboard (Update A)
ICSA-26-258-02 · CISA · September 15, 2026
Summary
Successful exploitation of these vulnerabilities could allow an attacker to deliver an unauthorized update, execute code, or extract credentials to allow the attacker to impersonate a privileged client.
From CISA, quoted as published. Check the source before acting.
What to do
Wärtsilä states that the vulnerabilities are not exploitable when the product is installed as recommended, and has developed a security patch. The patch (version 5.08.4052.01) can be found on the Wärtsilä FOS download site. Users can also contact Wärtsilä to obtain and install the patch.
Vendor fix or mitigation, quoted from the advisory.
Each CVE in this advisory
| CVE | Severity | Known exploited | Exploit likelihood |
|---|---|---|---|
| CVE-2026-78225 | 8.3 high | No | 0.5% |
| CVE-2026-81855 | 8.3 high | No | 0.6% |
Severity from the advisory (CVSS), known exploitation from CISA's catalog, exploit likelihood from EPSS (next 30 days).
Affected products
| Vendor | Product |
|---|---|
| Wärtsilä | FOS-Onboard |
Why it's on these mode pages
- Maritime: Vendor table: Wärtsilä (matched by rule)
Change history
- September 15, 2026: Initial Publication
- September 24, 2026: Update A - Added link and version number for fixed version.
- November 9, 2026: First collected by Watch
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