CVE-2026-77353 ellite CVE debrief

Who should care

Users of Wallos versions prior to 5.0.0, administrators of Wallos installations, and security teams responsible for vulnerability management and monitoring should be aware of this vulnerability and take necessary actions to mitigate it. They should review the official advisory and CVE record to validate affected scope, severity, and vendor guidance, and plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Technical summary

Wallos allows authenticated users to inject arbitrary iCalendar properties and events into .ics feeds via embedded CRLF sequences. This vulnerability affects users of Wallos versions prior to 5.0.0 and administrators of Wallos installations. To verify, defenders should review the official advisory and CVE record for affected scope, severity, and vendor guidance. They should also check relevant monitoring, detection, and logs for exposed assets that need extra review. The vulnerability can be exploited by users with valid accounts, allowing them to craft subscriptions whose names break out of the current VEVENT block and insert fully attacker-controlled calendar events into any calendar application subscribed to that feed.

Defensive priority

Authenticated users can inject arbitrary iCalendar properties and events into .ics feeds; validate and sanitize user input.

Recommended defensive actions

• Validate and sanitize user input for .ics feed generation
• Implement proper encoding for iCalendar properties and events
• Monitor .ics feed exports for suspicious activity
• Update to Wallos version 5.0.0 or later
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

Wallos allows authenticated users to inject arbitrary iCalendar properties and events into .ics feeds via embedded CRLF sequences. The vulnerability affects users of Wallos versions prior to 5.0.0 and administrators of Wallos installations. To verify, defenders should review the official advisory and CVE record for affected scope, severity, and vendor guidance. They should also check relevant monitoring, detection, and logs for exposed assets that need extra review.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.