CVE-2026-40019

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "modules": ["core"], "product": "OX Dovecot CE", "vendor": "Open-Xchange GmbH", "versions": [{"lessThan": "2.4.5", "status": "affected", "version": "2.4.3", "versionType": "semver"}]}], "source": "security@open-xchange.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which makes it spin in an infinite loop consuming CPU. This can cause degradation or denial of service for Sieve script management, and repeated connections can consume all available CPU on the server. Monitor system for abnormal CPU usage and kill the offending process. Restrict network access to the ManageSieve service to trusted clients. Update to non-vulnerable version. No publicly available exploits are known."}], "id": "CVE-2026-40019", "lastModified": "2026-09-03T18:13:44.643", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 5.9, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 3.6, "source": "security@open-xchange.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-40019", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-08-28T14:58:09.351983Z", "version": "2.0.3"}}]}, "published": "2026-08-28T12:16:28.770", "references": [{"source": "security@open-xchange.com", "url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json"}], "sourceIdentifier": "security@open-xchange.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-400"}], "source": "security@open-xchange.com", "type": "Secondary"}]}

{"bugzilla": {"description": "dovecot: Dovecot: Denial of Service via truncated quoted argument in ManageSieve", "id": "2525559", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525559"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-835", "details": ["An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which makes it spin in an infinite loop consuming CPU. This can cause degradation or denial of service for Sieve script management, and repeated connections can consume all available CPU on the server. Monitor system for abnormal CPU usage and kill the offending process. Restrict network access to the ManageSieve service to trusted clients. Update to non-vulnerable version. No publicly available exploits are known.", "A flaw was found in Dovecot's ManageSieve login process. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted, truncated quoted argument. This action causes the process to enter an infinite loop, consuming excessive CPU resources. Repeated exploitation can lead to a denial of service, impacting Sieve script management and overall server availability."], "mitigation": {"lang": "en:us", "value": "Restrict network access to the ManageSieve service to trusted clients only. This can be accomplished by configuring a firewall to limit incoming connections to the port used by ManageSieve (typically 4190/tcp) from known, authorized IP addresses or subnets. This action reduces the attack surface by preventing untrusted remote access to the vulnerable service. A service restart or reload may be required for firewall changes to take full effect, depending on the firewall management tool used."}, "name": "CVE-2026-40019", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "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": "Affected", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-28T10:12:21Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-40019\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-40019\nhttps://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2.4.3,2.4.5)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "OX Dovecot CE", "source": "cna", "vendor": "Open-Xchange GmbH"}, "product": "ox_dovecot_ce", "vendor": "open-xchange"}], "created": "2026-08-28T14:15:04.391063+00:00", "updated": "2026-09-01T14:45:04.125541+00:00", "vendors": ["open-xchange", "open-xchange$PRODUCT$ox_dovecot_ce"]}