CVE-2026-27858 | Open-Xchange OX Dovecot Pro up to 2.3.0/2.4.0/3.1.0 Message resource consumption (adv-2026-0001)

VDB-353847 · CVE-2026-27858 · ADV-2026-0001 OPEN-XCHANGE OX DOVECOT PRO UP TO 2.3.0/2.4.0/3.1.0 MESSAGE RESOURCE CONSUMPTION HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 6.3 $0-$5k 2.34+ Summaryinfo A vulnerability marked as problematic has been reported in Open-Xchange OX Dovecot Pro up to 2.3.0/2.4.0/3.1.0. Affected is an unknown function of the component Message Handler. Performing a manipulation results in resource consumption. This vulnerability is reported as CVE-2026-27858. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component. Detailsinfo A vulnerability, which was classified as problematic, was found in Open-Xchange OX Dovecot Pro up to 2.3.0/2.4.0/3.1.0. This affects an unknown code of the component Message Handler. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. The summary by CVE is: 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. It is possible to read the advisory at documentation.open-xchange.com. This vulnerability is uniquely identified as CVE-2026-27858 since 02/24/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK. Upgrading eliminates this vulnerability. Productinfo Type Mail Server Software Vendor Open-Xchange Name OX Dovecot Pro Version 2.0 2.1 2.2 2.3 2.3.0 2.4.0 3.0 3.1.0 License open-source Website Vendor: https://www.open-xchange.com/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 6.4 VulDB Meta Temp Score: 6.3 VulDB Base Score: 5.3 VulDB Temp Score: 5.1 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 7.5 CNA Vector: 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Resource consumption CWE: CWE-400 / CWE-404 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Timelineinfo 02/24/2026 CVE reserved 03/27/2026 +31 days Advisory disclosed 03/27/2026 +0 days VulDB entry created 03/27/2026 +0 days VulDB entry last update Sourcesinfo Vendor: open-xchange.com Advisory: adv-2026-0001 Status: Confirmed CVE: CVE-2026-27858 (🔒) GCVE (CVE): GCVE-0-2026-27858 GCVE (VulDB): GCVE-100-353847 Entryinfo Created: 03/27/2026 09:51 Changes: 03/27/2026 09:51 (64) Complete: 🔍 Cache ID: 99:49A:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸