CVE-2026-61910: cyrus imap Incorrect Authorization

Vulnerability summary

CVE-2026-61910 is a medium (CVSS 5.0) Incorrect Authorization vulnerability in cyrus imap. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 8.2% of scored vulnerabilities.

Timeline

1. 09-09-2026
   PublishedVulnerability first disclosed.
2. 14-09-2026
   Last modifiedVulnerability information updated.

Description

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.)

• CWE-863Incorrect AuthorizationThe product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.