Auth bypass in Cyrus Imap
CVE-2026-61910
An issue was discovered in Cyrus IMAP before 3.12.4. Mailbox/set let a sharee change a special-use role on shared mailboxes. An authenticated user with maySetKeywords on another user's mailbox could change that mailbox's specialuse annotation. This could allow the sharee to change the shared mailbox to perform the archived, snoozed, or other role, which might cause mail mail to be written to the shared mailbox, sharing more content than intended. (This is likely to be an unusual situation, made more unusual because if the target already has an non-shared mailbox with that role, role duplication suppression will prevent the update.)
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.5 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.002 (8.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 8th percentile — 8.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.002 · change: -0.001
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-2026-61910?
- CVE-2026-61910 is a low-severity vulnerability in Cyrus Imap, classified under Incorrect Authorization. CVSS score: 3.5/10. Published 2026-09-09.
- How severe is CVE-2026-61910?
- Low severity. CVSS v3 base score is 3.5 out of 10.