CVE-2026-27858
HIGH severity · CVSS 7.5 · Uncontrolled resource consumption
7.5CVSS HIGH
Summary
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.
Impact & exploitability
Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
Confidentiality impactNone
Integrity impactNone
Availability impactHigh
Exploit probability (EPSS)1%
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products we track (1)
Recommendation
Apply the vendor fix promptly. Open any affected product above for its exact safe version.
Additional information
- NVD record
- https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.jsonAdvisory
- https://access.redhat.com/errata/RHSA-2026:13498
- https://access.redhat.com/errata/RHSA-2026:13830
- https://access.redhat.com/errata/RHSA-2026:13857
- https://access.redhat.com/errata/RHSA-2026:17602
- https://access.redhat.com/errata/RHSA-2026:17625
- https://access.redhat.com/errata/RHSA-2026:17626
- https://access.redhat.com/errata/RHSA-2026:17628