Vulnerability in Cyrus Imap
CVE-2026-61911
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.002 (11.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 11.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.002 · change: -0.002
Affected products
Weakness classification (CWE)
References
- cyrusimap.org (Product)
- www.cyrusimap.org/3.12/imap/download/release-notes/3.12/x/3.12.4.html (Release Notes)
- www.cyrusimap.org/3.12/imap/download/release-notes/3.10/x/3.10.4.html (Release Notes)
- www.cyrusimap.org/3.12/imap/download/release-notes/3.8/x/3.8.8.html (Release Notes)
Frequently asked questions
- What is CVE-2026-61911?
- CVE-2026-61911 is a medium-severity vulnerability in Cyrus Imap, classified under Exposure of Sensitive System Information to an Unauthorized Control Sphere. CVSS score: 4.3/10. Published 2026-09-09.
- How severe is CVE-2026-61911?
- Medium severity. CVSS v3 base score is 4.3 out of 10.