CVE-2026-110777

A flaw was found in evolution-data-server. Calendar events containing a file:// URI in their ATTACH property automatically read the targeted local file, base64-encode its contents and upload it back to the server when the event is saved. There are no file path restrictions or checks to verify whether the attachment originally came from the server or was added locally. This allows an attacker with access to a shared CalDAV calendar to exfiltrate arbitrary files the user has access to when interacting with malicious calendar events.

To exploit this vulnerability, an attacker needs to create a calendar event containing an attachment with a file:// URI pointing to a local file. To trigger this issue, the user needs to interact with the malicious calendar event, allowing the attacker to exfiltrate arbitrary files the user has access to. For these reasons, this flaw has been rated with a moderate severity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.