An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. (CVE-2026-47082)
Description
Cyrus IMAP through version 3.12.2 contains a vulnerability in the vacation "fcc" feature where the destination mailbox ACL is bypassed. This allows a user with a vacation Sieve script using :fcc to save copies of sent messages into any mailbox named by the script, regardless of insert permissions on that mailbox. The vulnerability has a medium severity with a CVSS score of 5.4.
CVSS v3.1
Score 5.4medium
Affected software
pkg:deb/ubuntu/cyrus-imapd?arch=source&distro=esm-apps/bionicpkg:deb/ubuntu/cyrus-imapd?arch=source&distro=esm-apps/focalpkg:deb/ubuntu/cyrus-imapd?arch=source&distro=esm-apps/jammypkg:deb/ubuntu/cyrus-imapd?arch=source&distro=esm-apps/noblepkg:deb/ubuntu/cyrus-imapd?arch=source&distro=stonkingpkg:deb/ubuntu/cyrus-imapd?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in cyrus-imapd (CVE-2026-47082) affects versions through 3.12.2. The vacation "fcc" feature improperly skips checking the destination mailbox ACL, enabling a user whose vacation Sieve script uses the :fcc flag to deliver vacation auto-reply copies into arbitrary mailboxes. This occurs regardless of whether the script owner has insert permissions on the destination mailbox, potentially allowing unauthorized message delivery.
Potential Impact
An attacker with the ability to configure a vacation Sieve script can cause copies of vacation auto-replies to be delivered into any mailbox they specify, bypassing mailbox insert permission checks. This could lead to unauthorized message insertion and potential mailbox content manipulation. There is no indication of confidentiality or availability impact beyond this unauthorized insertion.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict the ability to configure vacation Sieve scripts to trusted users only, and monitor for unusual mailbox activity related to vacation auto-replies.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-47082
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:Pro:22.04:LTS","Ubuntu:Pro:24.04:LTS","Ubuntu:26.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ad3f64d2cdf04f656665861
Added to database: 10/17/2026, 22:27:25 UTC
Last enriched: 10/18/2026, 01:23:56 UTC
Last updated: 10/18/2026, 01:23:56 UTC
Views: 3
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