CVE-2026-73208

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "modules": ["core"], "product": "OX Dovecot Pro", "vendor": "Open-Xchange GmbH", "versions": [{"lessThan": "2.3.22.2", "status": "affected", "version": "2.3.13", "versionType": "semver"}, {"lessThan": "3.0.7", "status": "affected", "version": "3.0.0", "versionType": "semver"}, {"lessThan": "3.1.6", "status": "affected", "version": "3.1.0", "versionType": "semver"}]}, {"defaultStatus": "unaffected", "modules": ["core"], "product": "OX Dovecot CE", "vendor": "Open-Xchange GmbH", "versions": [{"lessThan": "2.4.5", "status": "affected", "version": "2.3.13", "versionType": "semver"}]}], "source": "security@open-xchange.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "An attacker that holds a token intended for a different purpose can authenticate, because when an OAuth2 token response does not contain a scope claim, the audience claim is used in its place and checked against the configured required scopes. These are different concepts, and the audience claim does not describe what a token is allowed to do. A token that grants no relevant permissions can be accepted because its intended recipient value happens to match a configured scope name, granting access that should have been denied. It also hides an identity provider misconfiguration where scopes are not being issued at all. Ensure the identity provider issues a scope claim for all tokens used with Dovecot, and that configured scope names do not match audience values. Update to non-vulnerable version. No publicly available exploits are known."}], "id": "CVE-2026-73208", "lastModified": "2026-09-03T18:13:44.643", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.4, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 5.2, "source": "security@open-xchange.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-73208", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-08-28T15:14:37.239590Z", "version": "2.0.3"}}]}, "published": "2026-08-28T12:16:31.127", "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-287"}], "source": "security@open-xchange.com", "type": "Secondary"}]}

{"bugzilla": {"description": "dovecot: Dovecot: Authentication bypass via incorrect OAuth2 token validation", "id": "2525547", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525547"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N", "status": "draft"}, "cwe": "CWE-303", "details": ["An attacker that holds a token intended for a different purpose can authenticate, because when an OAuth2 token response does not contain a scope claim, the audience claim is used in its place and checked against the configured required scopes. These are different concepts, and the audience claim does not describe what a token is allowed to do. A token that grants no relevant permissions can be accepted because its intended recipient value happens to match a configured scope name, granting access that should have been denied. It also hides an identity provider misconfiguration where scopes are not being issued at all. Ensure the identity provider issues a scope claim for all tokens used with Dovecot, and that configured scope names do not match audience values. Update to non-vulnerable version. No publicly available exploits are known.", "A flaw was found in Dovecot. This vulnerability allows an attacker to bypass authentication by exploiting how OAuth2 tokens are validated. If an OAuth2 token response does not include a scope claim, Dovecot incorrectly uses the audience claim in its place for authorization checks. This can lead to unauthorized access, as a token with no relevant permissions might be accepted if its intended recipient value matches a configured scope name."], "mitigation": {"lang": "en:us", "value": "To mitigate this issue, ensure that the identity provider issues a scope claim for all tokens used with Dovecot. Additionally, verify that configured scope names in Dovecot do not match audience values from the identity provider. A restart of the Dovecot service may be required for configuration changes to take effect."}, "name": "CVE-2026-73208", "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": "Not affected", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not 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": "2026-08-28T10:12:32Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-73208\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-73208\nhttps://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json"], "threat_severity": "Important"}

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