CVE-2026-61911

cyrus-imapd: cyrus-imapd: Sieve fileinto mailbox existence oracle

Published Sep 9, 2026 CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Cyrus
Cyrus imap
CPEs cpe:2.3:a:cyrus:imap:*:*:*:*:*:*:*:*
Vendors & Products Cyrus
Cyrus imap
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Title Sieve Mailbox Existence Oracle in Cyrus IMAP cyrus-imapd: cyrus-imapd: Sieve fileinto mailbox existence oracle
References
Metrics threat_severity

None

threat_severity

Moderate

Type Values Removed Values Added
Title Sieve Mailbox Existence Oracle in Cyrus IMAP
Type Values Removed Values Added
First Time appeared Cyrusimap
Cyrusimap cyrus Imap
Weaknesses CWE-497
CPEs cpe:2.3:a:cyrusimap:cyrus_imap:*:*:*:*:*:*:*:*
Vendors & Products Cyrusimap
Cyrusimap cyrus Imap
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'}

Type Values Removed Values Added
Description 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.
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Sep 10, 2026, 7:01 PM
Reserved
Jul 13, 2026, 12:00 AM
Status
Analyzed
Published
Sep 9, 2026, 8:18 PM
Modified
Sep 16, 2026, 3:23 PM
Severity
Moderate
Public date
Sep 10, 2026, 7:43 AM