# CVE-2026-61911

## Summary

- **CVE ID:** CVE-2026-61911
- **Severity:** MEDIUM
- **CVSS Score:** 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)
- **CWE:** CWE-497
- **Published:** Sep 9, 2026
- **Last Modified:** Sep 10, 2026

## 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.

## Affected Products

- cyrusimap — Cyrus IMAP (0)
- cyrusimap — Cyrus IMAP (3.9.0)
- cyrusimap — Cyrus IMAP (3.11.0)

## References

- [CNA](https://cyrusimap.org)
- [CNA](https://www.cyrusimap.org/3.12/imap/download/release-notes/3.12/x/3.12.4.html)
- [CNA](https://www.cyrusimap.org/3.12/imap/download/release-notes/3.10/x/3.10.4.html)
- [CNA](https://www.cyrusimap.org/3.12/imap/download/release-notes/3.8/x/3.8.8.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.22%
- **EPSS Percentile:** 12.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._