CVE-2026-110777 Red Hat CVE debrief

Who should care

Defenders managing evolution-data-server instances, especially in shared CalDAV calendar environments, should assess exposure and prioritize updates to prevent file disclosure. This includes reviewing the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance, and planning vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Why it matters

CVE-2026-110777 allows attackers to exfiltrate arbitrary files from evolution-data-server instances via malicious calendar events, impacting defenders managing shared CalDAV calendars.

• Verify and update evolution-data-server instances to prevent file disclosure
• Restrict access to shared CalDAV calendars to limit attack vectors
• Monitor for suspicious calendar events to detect potential exploitation

Technical summary

A flaw in evolution-data-server allows attackers to exfiltrate arbitrary files via malicious calendar events containing file:// URIs in their ATTACH property. This vulnerability impacts defenders managing shared CalDAV calendars, as it enables the exfiltration of arbitrary files from evolution-data-server instances. To address this vulnerability, defenders should prioritize verifying and updating evolution-data-server instances, especially in shared CalDAV calendar environments, and restrict access to shared CalDAV calendars.

Defensive priority

Defenders should prioritize verifying and updating evolution-data-server instances, especially in shared CalDAV calendar environments.

Recommended defensive actions

• Verify and update evolution-data-server instances to the latest version
• Restrict access to shared CalDAV calendars
• Monitor for suspicious calendar events
• 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
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and source item provide details on the flaw in evolution-data-server, allowing attackers to exfiltrate arbitrary files via malicious calendar events. The source item provides additional context on the vulnerability, including its impact on evolution-data-server instances. To verify the vulnerability, defenders should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

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.