United States
USA
Ransomware disables ImageMaster MuniOS municipal-bond disclosure platform
A ransomware attack against ImageMaster disabled MuniOS, a platform used by municipal-bond issuers to publish disclosure and offering documents. Attackers exploited a firewall vulnerability and encrypted the company's servers, leaving MuniOS unavailable for several days and forcing issuers and market participants to use alternative publication channels until systems were rebuilt.
74
Estimated severity
74 / 100
91
Source reliability
91 / 100
Approximate Date
15/10/2025
Targeted Company
IMAGEMASTER
Targeted Company Supply Chain Impact
Distribution & Fulfillment
Procurement & Sourcing
Production & Manufacturing
Sales (Retail & Ecommerce)
Warehousing
Service Delivery
Unrecognized Impact
Supply Chain Relations
No information
Geographic Impact
Country Targeted Company
Other Affected Countries
No other affected countries reported
Target country
United States
Affected countries
United States
Impacted regions
No information
Operational Impact
Duration
No information
Financial impact (USD M)
No information
Impact types
Service unavailabilityDownstream customer disruptionOperational disruption
Affected sectors
Technology & IT ServicesFinance & Insurance
Affected departments
Information Technology
Attack Profile
Attack types
RansomwareExploitation of vulnerability
Attributed threat actors
No information
Sources
Incident Sources
news.bloomberglaw.comhttps://news.bloomberglaw.com/tech-and-telecom-law/key-muni-market-website-munios-is-back-online-after-outagebloomberg.comhttps://www.bloomberg.com/news/articles/2025-10-15/ransomware-attack-ensnares-4-3-trillion-muni-market-s-key-sitemcguirewoods.comhttps://www.mcguirewoods.com/news/in-the-news/2025/10/in-bond-buyer-article-mcguirewoods-partners-offer-insights-on-munios-cyberattack/insurancejournal.comhttps://www.insurancejournal.com/news/national/2025/10/16/843867.htm