Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Dovecot | Dovecot | < 2.4.3 |
| Open-Xchange | Dovecot | < 2.3.22.1 |
Related Weaknesses (CWE)
References
- https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdVendor Advisory
- 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
- https://access.redhat.com/errata/RHSA-2026:17630
- https://access.redhat.com/errata/RHSA-2026:18053
- https://access.redhat.com/errata/RHSA-2026:19149
- https://access.redhat.com/errata/RHSA-2026:19364
- https://access.redhat.com/errata/RHSA-2026:19453
- https://access.redhat.com/errata/RHSA-2026:19455
- https://access.redhat.com/errata/RHSA-2026:26564
FAQ
What is CVE-2026-27858?
CVE-2026-27858 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 repeatedl...
How severe is CVE-2026-27858?
CVE-2026-27858 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-27858?
Check the references section above for vendor advisories and patch information. Affected products include: Dovecot Dovecot, Open-Xchange Dovecot.