An issue was discovered in Cyrus IMAP before 3.12.4. There is a Sieve mailbox existence oracle. An authenticated user could install a Sieve script that probed whether another user's private mailbox existed, or read the value of shared mailbox annotations, by observing which fileinto branch fired during LMTP delivery.

The AlmaLinux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1790173408 advisory.

  - An issue was discovered in Cyrus IMAP before 3.12.4. CalDAV/CardDAV multiget bypasses a per-href ACL. An     authenticated DAV user with some shared access to another user's calendar or address book could read even     unshared events or contacts by including the target hrefs in a calendar-multiget or addressbook-multiget     REPORT. (CVE-2026-61909)

  - An issue was discovered in Cyrus IMAP before 3.12.4. There is a Sieve mailbox existence oracle. An     authenticated user could install a Sieve script that probed whether another user's private mailbox     existed, or read the value of shared mailbox annotations, by observing which fileinto branch fired during     LMTP delivery. (CVE-2026-61911)

  - An issue was discovered in Cyrus IMAP before 3.12.4. There is a VPATCH BYPARAM double-free. An     authenticated calendar user could crash a Cyrus CalDAV worker with a PATCH containing PATCH-     ACTION=BYPARAM@... against a resource with two or more properties of the matched kind. The memory     holding the selector would be freed once on each iteration over the properties. (CVE-2026-61915)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Rocky Linux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1790173408 advisory.

  - An issue was discovered in Cyrus IMAP before 3.12.4. CalDAV/CardDAV multiget bypasses a per-href ACL. An     authenticated DAV user with some shared access to another user's calendar or address book could read even     unshared events or contacts by including the target hrefs in a calendar-multiget or addressbook-multiget     REPORT. (CVE-2026-61909)

  - An issue was discovered in Cyrus IMAP before 3.12.4. There is a Sieve mailbox existence oracle. An     authenticated user could install a Sieve script that probed whether another user's private mailbox     existed, or read the value of shared mailbox annotations, by observing which fileinto branch fired during     LMTP delivery. (CVE-2026-61911)

  - An issue was discovered in Cyrus IMAP before 3.12.4. There is a VPATCH BYPARAM double-free. An     authenticated calendar user could crash a Cyrus CalDAV worker with a PATCH containing PATCH-     ACTION=BYPARAM@... against a resource with two or more properties of the matched kind. The memory     holding the selector would be freed once on each iteration over the properties. (CVE-2026-61915)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote openSUSE 16 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:21929-1 advisory.

    Changes in cyrus-imapd:

    Update to 3.8.8 (bugfix release):

    - CVE-2026-61907: JMAP snooze bypasses destination-mailbox ACL (bsc#1279908)
    - CVE-2026-61908: JMAP email-header blob ID out-of-bounds index (bsc#1279975)
    - CVE-2026-61909: CalDAV/CardDAV multiget bypasses per-href ACL (bsc#1279976)
    - CVE-2026-61910: Mailbox/set let sharee change special-use role on shared mailboxes (bsc#1279977)
    - CVE-2026-61911: Sieve mailbox existence oracle (bsc#1279978)
    - CVE-2026-61915: VPATCH BYPARAM double-free (bsc#1279979)

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 45 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-3bf3e31ef4 advisory.

    - New version 3.12.4 (rhbz#2500822)



Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-97a7ec5786 advisory.

    - New version 3.10.4 (rhbz#2500822)



Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-740bc1c6fa advisory.

    - New version 3.12.4 (rhbz#2500822)



Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - An issue was discovered in Cyrus IMAP before 3.12.4. There is a Sieve mailbox existence oracle. An     authenticated user could install a Sieve script that probed whether another user's private mailbox     existed, or read the value of shared mailbox annotations, by observing which fileinto branch fired during     LMTP delivery. (CVE-2026-61911)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
361352	AlmaLinux 9.6 [TuxCare] Security Update: cyrus-imapd / cyrus-imapd-devel / cyrus-imapd-doc-extra / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1790173408)	Nessus	Alma Linux Local Security Checks	Local	high
361304	Rocky Linux 9.6 [TuxCare] Security Update: cyrus-imapd / cyrus-imapd-devel / cyrus-imapd-doc-extra / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1790173408)	Nessus	Rocky Linux Local Security Checks	Local	high
350143	openSUSE 16: cyradm / cyrus-imapd / cyrus-imapd-devel / cyrus-imapd-snmp / etc (openSUSE-SU-2026:21929-1)	Nessus	SuSE Local Security Checks	Local	high
349129	Fedora 45 : cyrus-imapd (2026-3bf3e31ef4)	Nessus	Fedora Local Security Checks	Local	high
349123	Fedora 43 : cyrus-imapd (2026-97a7ec5786)	Nessus	Fedora Local Security Checks	Local	high
349116	Fedora 44 : cyrus-imapd (2026-740bc1c6fa)	Nessus	Fedora Local Security Checks	Local	high
344527	Linux Distros Unpatched Vulnerability : CVE-2026-61911	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2026-61911

medium

Tenable Plugins

high

high

high

high

high

high

medium