Medium [CVE-2026-61909] CalDAV/CardDAV multiget bypasses per-href ACL
This medium-severity Red Hat Linux advisory covers CVE-2026-61909 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
A flaw was found in cyrus-imapd. An authenticated DAV (Distributed Authoring and Versioning) user with some shared access to another user's calendar or address book could read unshared events or contacts.
This information disclosure occurs by including specific resource identifiers in a calendar-multiget or addressbook-multiget REPORT, bypassing intended access controls. Red Hat severity: Moderate — CVSS 5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N).
Weakness: CWE-420. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.
Will not fix / out of support: Red Hat Enterprise Linux 6. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: cyrus-imapd.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Mitigation checklist
- To reduce the attack surface, restrict network access to the cyrus-imapd service to trusted internal networks or localhost. This operational control can be implemented by configuring network firewalls to limit inbound connections to the service's listening port. This may impact legitimate users who require remote CalDAV/CardDAV access.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
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