Is CVE-2026-61909 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-61909 being exploited in the wild.

How severe is CVE-2026-61909?

Low severity, with a CVSS score of 3.5, published 9 September 2026.

Is there a fix for CVE-2026-61909?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-61909 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-61909?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-61909: Cyrus IMAP CalDAV/CardDAV multiget ACL bypass

CVE-2026-61909 · Severity: low · CVSS 3.5 · Published 2026-09-09

Cyrus IMAP is an email, contacts, and calendar server used in production environments globally. An authenticated user with partial access to another user's calendar or address book can read unshared events and contacts by exploiting a flaw in the multiget REPORT feature, potentially exposing sensitive schedule and contact information despite access restrictions.

Quick answers

Is CVE-2026-61909 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-61909 being exploited in the wild.
How severe is CVE-2026-61909?: Low severity, with a CVSS score of 3.5, published 9 September 2026.
Which products and versions are affected?: Cyrus IMAP before 3.12.4.
Is there a fix for CVE-2026-61909?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-61909 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-61909?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is an access control list (ACL) bypass in the CalDAV/CardDAV multiget REPORT handler. An authenticated DAV user with delegated access to another user's calendar or address book can circumvent per-href ACL checks by including target hrefs in a calendar-multiget or addressbook-multiget REPORT request, allowing them to read events or contacts that were not explicitly shared with them. The attack requires existing authenticated DAV access and network reachability to the Cyrus IMAP server. The vulnerability is fixed in Cyrus IMAP 3.12.4 and later versions.

Affected products

Cyrus IMAP before 3.12.4

Timeline

2026-09-09: disclosed

References

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