CVE-2026-40205

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{"bugzilla": {"description": "dovecot: Dovecot: Authorization bypass via partially valid OAuth2 token", "id": "2525548", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525548"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.9", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N", "status": "draft"}, "cwe": "CWE-303", "details": ["An attacker that holds an OAuth2 token granting only part of the required scopes can authenticate, because when more than one scope is required in the configuration, the remote token validation paths accept a token that carries only one of them, while the local token validation path correctly requires all of them. The configured authorization policy is not enforced, so a token that was granted only part of the required permissions is accepted where it should have been rejected. Use local token validation where tokens can be validated locally. Update to non-vulnerable version. No publicly available exploits are known.", "A flaw was found in Dovecot. An attacker with a partially valid OAuth2 token can bypass authorization checks in remote token validation paths. This allows the attacker to authenticate with insufficient permissions, leading to a breach of integrity where the configured authorization policy is not properly enforced."], "mitigation": {"lang": "en:us", "value": "To mitigate this issue, configure Dovecot to use local OAuth2 token validation instead of remote validation. This ensures that all required scopes are correctly enforced during authentication, preventing unauthorized access with partially valid tokens. Consult Dovecot documentation for specific configuration steps to enable local token validation. A service restart may be required for the changes to take effect."}, "name": "CVE-2026-40205", "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": "2026-08-28T10:12:24Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-40205\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-40205\nhttps://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json"], "threat_severity": "Moderate"}

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