Bug 2526667 - CVE-2026-33263 dovecot: Dovecot: Denial of Service and potential message duplication via connection limit exhaustion [fedora-all]
Summary: CVE-2026-33263 dovecot: Dovecot: Denial of Service and potential message dupl...
Keywords:
Status: ON_QA
Alias: None
Product: Fedora
Classification: Fedora
Component: dovecot
Version: rawhide
Hardware: Unspecified
OS: Unspecified
high
high
Target Milestone: ---
Assignee: Michal Hlavinka
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["dd498042-51ec-4167-b090-6...
Depends On:
Blocks: CVE-2026-33263
TreeView+ depends on / blocked
 
Reported: 2026-09-01 07:24 UTC by Vladimir Vasilev
Modified: 2026-09-11 02:27 UTC (History)
3 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type: ---
Embargoed:


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Description Vladimir Vasilev 2026-09-01 07:24:13 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor handling issues. If running in high-security mode (default for community releases), only the new submission connection gets terminated. If running in high-performance mode (default for Pro releases), all connections handled by the submission-login process will be terminated. The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent. If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen, because the crash can only happen at AUTH stage. Limit the number of connections handled by single submission-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.

Comment 1 Fedora Update System 2026-09-10 05:35:27 UTC
FEDORA-2026-e8a6485109 (dovecot-2.4.5-1.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-e8a6485109

Comment 2 Fedora Update System 2026-09-11 01:34:17 UTC
FEDORA-2026-8b8efbd2b8 has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-8b8efbd2b8`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-8b8efbd2b8

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 3 Fedora Update System 2026-09-11 02:07:07 UTC
FEDORA-2026-e8a6485109 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-e8a6485109`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-e8a6485109

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 4 Fedora Update System 2026-09-11 02:27:01 UTC
FEDORA-2026-2e6b786570 has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-2e6b786570`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-2e6b786570

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.


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