{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-27859", "assignerOrgId": "8ce71d90-2354-404b-a86e-bec2cc4e6981", "state": "PUBLISHED", "assignerShortName": "OX", "dateReserved": "2026-02-24T08:46:09.374Z", "datePublished": "2026-03-27T08:10:22.058Z", "dateUpdated": "2026-03-27T12:35:14.776Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "modules": ["core"], "product": "OX Dovecot Pro", "vendor": "Open-Xchange GmbH", "versions": [{"lessThanOrEqual": "3.0.2", "status": "affected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "3.1.0", "status": "affected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "2.4.0", "status": "affected", "version": "0", "versionType": "semver"}]}], "descriptions": [{"lang": "en", "value": "A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. A suitably formatted mail message causes mail delivery process to consume large amounts of CPU time. Use MTA capabilities to limit RFC 2231 MIME parameters in mail messages, or upgrade to fixed version where the processing is limited. No publicly available exploits are known."}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "version": "3.1"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-400", "description": "Uncontrolled Resource Consumption", "lang": "en", "type": "cwe"}]}], "providerMetadata": {"orgId": "8ce71d90-2354-404b-a86e-bec2cc4e6981", "shortName": "OX", "dateUpdated": "2026-03-27T12:33:32.573Z"}, "references": [{"tags": ["vendor-advisory"], "url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json"}], "source": {"defect": "DOV-8787", "discovery": "EXTERNAL"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-03-27T12:34:31.543674Z", "id": "CVE-2026-27859", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-27T12:35:14.776Z"}}]}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. A suitably formatted mail message causes mail delivery process to consume large amounts of CPU time. Use MTA capabilities to limit RFC 2231 MIME parameters in mail messages, or upgrade to fixed version where the processing is limited. No publicly available exploits are known."}], "id": "CVE-2026-27859", "lastModified": "2026-03-30T13:26:29.793", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 1.4, "source": "security@open-xchange.com", "type": "Secondary"}]}, "published": "2026-03-27T09:16:20.223", "references": [{"source": "security@open-xchange.com", "url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json"}], "sourceIdentifier": "security@open-xchange.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-400"}], "source": "security@open-xchange.com", "type": "Secondary"}]}

{"bugzilla": {"description": "dovecot: Dovecot: Denial of Service via excessive RFC 2231 MIME parameters", "id": "2452180", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2452180"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "status": "draft"}, "cwe": "CWE-770", "details": ["A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. A suitably formatted mail message causes mail delivery process to consume large amounts of CPU time. Use MTA capabilities to limit RFC 2231 MIME parameters in mail messages, or upgrade to fixed version where the processing is limited. No publicly available exploits are known.", "A flaw was found in Dovecot. A remote attacker can exploit this vulnerability by sending a specially crafted mail message containing an excessive amount of RFC 2231 MIME parameters. This can cause the Local Mail Transfer Protocol (LMTP) process to consume large amounts of CPU time, leading to a Denial of Service (DoS)."], "name": "CVE-2026-27859", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-03-27T08:10:22Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-27859\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-27859\nhttps://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,3.0.2]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,3.1.0]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,2.4.0]"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "OX Dovecot Pro", "source": "cna", "vendor": "Open-Xchange GmbH"}, "product": "ox_dovecot_pro", "vendor": "open-xchange"}], "analysis": {"en": {"generated_at": "2026-03-28T13:29:13.052110+00:00", "value": {"mitigation_remediation": ["Configure the MTA to limit the number of RFC 2231 MIME parameters allowed in incoming messages", "Upgrade to a fixed version of OX Dovecot Pro once it becomes available"], "summary": {"action": "Patch", "impact": "Denial of Service"}, "threat_synthesis": {"affected_systems": "The vulnerability affects the OX Dovecot Pro mail server from Open\u2011Xchange GmbH. No specific version numbers of the vulnerable build are listed in the advisory. Users of any among these deployments are potentially impacted until a patch or configuration fix is applied.", "description_and_impact": "A mail message that contains an excessive number of RFC 2231 MIME parameters causes the LMTP component of the mail server to consume an abnormal amount of CPU time. The result is a denial of service scenario in which the delivery process is exhausted and can no longer serve legitimate mail traffic. The underlying weakness is an uncontrolled resource consumption scenario, identified with CWE\u2011400 and CWE\u2011770.", "risk_and_exploitability": "The CVSS score of 5.3 indicates a moderate severity, and the EPSS score of less than 1% suggests a very low probability of exploitation in the wild. The vulnerability is not catalogued in CISA's KEV list, and no public exploits have been published. Because the vulnerability requires sending a specially crafted message, an attacker would need to successfully inject mail into the system or have some way to trigger the LMTP processing path. The impact is limited to resource exhaustion rather than confidentiality or integrity compromise."}}}}, "created": "2026-03-27T15:47:09.178307+00:00", "updated": "2026-03-30T07:02:12.452716+00:00", "vendors": ["open-xchange", "open-xchange$PRODUCT$ox_dovecot_pro"]}