CVE-2026-27858
High
Description
Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory. Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.
SeverityHigh
CVSS7.5
Exploit probability—
ProductDovecot
PublishedMar 27, 2026
First seenMar 27, 2026
Weakness typeCWE-400Uncontrolled resource consumption
How to fix
Update
- dovecot dovecot2.4.3 or later
- open-xchange dovecot2.3.22.1, 3.0.5, 3.1.4 or later
Vendor advisories
- documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
- access.redhat.com/errata/RHSA-2026:26564
- access.redhat.com/errata/RHSA-2026:17602
- access.redhat.com/errata/RHSA-2026:13498
- access.redhat.com/errata/RHSA-2026:19149
- access.redhat.com/errata/RHSA-2026:13830
- access.redhat.com/errata/RHSA-2026:19455
- access.redhat.com/errata/RHSA-2026:19453
- access.redhat.com/errata/RHSA-2026:18053
- access.redhat.com/errata/RHSA-2026:17630
- access.redhat.com/errata/RHSA-2026:17628
- access.redhat.com/errata/RHSA-2026:17625
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| dovecot dovecot | v < 2.4.3 | 2.4.3 |
| open-xchange dovecot | v < 2.3.22.1, 3.0.0 ≤ v < 3.0.5, 3.1.0 ≤ v < 3.1.4 | 2.3.22.1, 3.0.5, 3.1.4 |
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