OX Dovecot Pro: Uncontrolled Resource Consumption
CVE-2026-33605 is a high-severity uncontrolled resource consumption vulnerability in OX Dovecot Pro from Open-Xchange, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 2.3.22.2, 3.0.7, 3.1.6 as the first without the flaw, so updating OX Dovecot Pro to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.45% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update OX Dovecot Pro to 2.3.22.2 or 3.0.7 or 3.1.6, whichever matches your release line, or a later version.
- Update OX Dovecot CE to 2.4.5 or a later version.
- Read the advisory on documentation.open-xchange.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Open-Xchange | OX Dovecot Pro | 2.3.0 up to, but not including, 2.3.22.2; 3.0.0 up to, but not including, 3.0.7; 3.1.0 up to, but not including, 3.1.6 | 2.3.22.2, 3.0.7, 3.1.6 |
| Open-Xchange | OX Dovecot CE | 2.3.0 up to, but not including, 2.4.5 | 2.4.5 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (open-xchange.com).
Official description
An unauthenticated attacker can crash the ManageSieve login process by sending a small malformed command before authenticating. If running in high-security mode (default for community releases), only the attacker's own connection is terminated. If running in high-performance mode (default for Pro releases), all connections handled by the same managesieve-login process are terminated. Repeating the attack can cause denial of service for Sieve script management. Restrict network access to the ManageSieve service to trusted clients. Update to non-vulnerable version. No publicly available exploits are known.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How developers prevent this class of flaw
- Ensure that protocols have specific limits of scale placed on them.
- Ensure that all failures in resource allocation place the system into a safe posture.
More Uncontrolled Resource Consumption vulnerabilities (CWE-400)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in OX Dovecot Pro
- 7.4 High severity
- 7.5 High severity
- 9.1 Critical severity
- 7.5 High severity
- 9.1 Critical severity
- 7.5 High severity
Recent Uncontrolled Resource Consumption vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.1 High severity
- 9.1 Critical severity
- 9.1 Critical severity
- 7.5 High severity
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