CVE-2021-20316

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{}

{"affected": [{"affectedData": [{"product": "samba", "vendor": "n/a", "versions": [{"status": "affected", "version": "Affects samba file server before v4.15.0, Fixed in samba v4.15.0"}]}], "source": "secalert@redhat.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*", "matchCriteriaId": "96835C03-A649-4975-B6DE-9E6A1F24D397", "versionEndExcluding": "4.15.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*", "matchCriteriaId": "07B237A9-69A3-4A9C-9DA0-4E06BD37AE73", "vulnerable": true}, {"criteria": "cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*", "matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:redhat:virtualization_host:4.0:*:*:*:*:*:*:*", "matchCriteriaId": "BB28F9AF-3D06-4532-B397-96D7E4792503", "vulnerable": true}, {"criteria": "cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*", "matchCriteriaId": "F4CFF558-3C47-480D-A2F0-BABF26042943", "vulnerable": true}, {"criteria": "cpe:2.3:o:redhat:enterprise_linux_aus:8.6:*:*:*:*:*:*:*", "matchCriteriaId": "5CA4F12A-5BC5-4D75-8F20-80D8BB2C5BF2", "vulnerable": true}, {"criteria": "cpe:2.3:o:redhat:enterprise_linux_eus:8.6:*:*:*:*:*:*:*", "matchCriteriaId": "6C3741B8-851F-475D-B428-523F4F722350", "vulnerable": true}, {"criteria": "cpe:2.3:o:redhat:enterprise_linux_tus:8.6:*:*:*:*:*:*:*", "matchCriteriaId": "C237415F-33FE-4686-9B19-A0916BF75D2D", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in the way Samba handled file/directory metadata. This flaw allows an authenticated attacker with permissions to read or modify share metadata, to perform this operation outside of the share."}, {"lang": "es", "value": "Se ha encontrado un fallo en la forma en que Samba maneja los metadatos de los archivos/directorios. Este fallo permite a un atacante autenticado con permisos para leer o modificar los metadatos del recurso compartido, llevar a cabo esta operaci\u00f3n fuera del recurso compartido."}], "id": "CVE-2021-20316", "lastModified": "2026-06-17T03:33:39.623", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.8, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 5.2, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2022-08-23T16:15:09.147", "references": [{"source": "secalert@redhat.com", "tags": ["Third Party Advisory"], "url": "https://access.redhat.com/security/cve/CVE-2021-20316"}, {"source": "secalert@redhat.com", "tags": ["Issue Tracking", "Third Party Advisory"], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2009673"}, {"source": "secalert@redhat.com", "tags": ["Issue Tracking", "Vendor Advisory"], "url": "https://bugzilla.samba.org/show_bug.cgi?id=14842"}, {"source": "secalert@redhat.com", "tags": ["Mitigation", "Third Party Advisory"], "url": "https://security-tracker.debian.org/tracker/CVE-2021-20316"}, {"source": "secalert@redhat.com", "url": "https://security.gentoo.org/glsa/202309-06"}, {"source": "secalert@redhat.com", "tags": ["Vendor Advisory"], "url": "https://www.samba.org/samba/security/CVE-2021-20316.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory"], "url": "https://access.redhat.com/security/cve/CVE-2021-20316"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Issue Tracking", "Third Party Advisory"], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2009673"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Issue Tracking", "Vendor Advisory"], "url": "https://bugzilla.samba.org/show_bug.cgi?id=14842"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mitigation", "Third Party Advisory"], "url": "https://security-tracker.debian.org/tracker/CVE-2021-20316"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://security.gentoo.org/glsa/202309-06"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Vendor Advisory"], "url": "https://www.samba.org/samba/security/CVE-2021-20316.html"}], "sourceIdentifier": "secalert@redhat.com", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-362"}], "source": "secalert@redhat.com", "type": "Secondary"}, {"description": [{"lang": "en", "value": "CWE-362"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"acknowledgement": "Red Hat would like to thank Michael Hanselmann (Google) for reporting this issue. Upstream acknowledges the Samba project as the original reporter.", "affected_release": [{"advisory": "RHSA-2022:2074", "cpe": "cpe:/a:redhat:enterprise_linux:8", "package": "samba-0:4.15.5-5.el8", "product_name": "Red Hat Enterprise Linux 8", "release_date": "2022-05-10T00:00:00Z"}, {"advisory": "RHSA-2022:2074", "cpe": "cpe:/o:redhat:enterprise_linux:8", "package": "samba-0:4.15.5-5.el8", "product_name": "Red Hat Enterprise Linux 8", "release_date": "2022-05-10T00:00:00Z"}, {"advisory": "RHSA-2022:1756", "cpe": "cpe:/a:redhat:storage:3.5:samba:el8", "package": "samba-0:4.15.5-100.el8rhgs", "product_name": "Red Hat Gluster Storage 3.5 for RHEL 8", "release_date": "2022-05-10T00:00:00Z"}], "bugzilla": {"description": "samba: Symlink race error can allow metadata read and modify outside of the exported share", "id": "2009673", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2009673"}, "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": "verified"}, "cwe": "CWE-362", "details": ["A flaw was found in the way Samba handled file/directory metadata. This flaw allows an authenticated attacker with permissions to read or modify share metadata, to perform this operation outside of the share.", "A flaw was found in the way Samba handled file/directory metadata. This flaw allows an authenticated attacker with permissions to read or modify share metadata, to perform this operation outside of the share."], "mitigation": {"lang": "en:us", "value": "Do not enable SMB1 (please note SMB1 is disabled by default in Samba from version 4.11.0 and onwards). This prevents the creation of symbolic links via SMB1. If SMB1 must be enabled for backward compatibility then add the parameter:\nunix extensions = no\nto the [global] section of your smb.conf and restart smbd. This prevents SMB1 clients from creating symlinks on the exported file system.\nHowever, if the same region of the file system is also exported using NFS, NFS clients can create symlinks that potentially can also hit the race condition. For non-patched versions of Samba, we recommend only exporting areas of the file system by either SMB2 or NFS, not both."}, "name": "CVE-2021-20316", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "samba", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "samba4", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "samba", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "samba", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2022-01-10T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-20316\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-20316\nhttps://www.samba.org/samba/security/CVE-2021-20316.html"], "statement": "As per upstream, \"Prior to Samba 4.15.0, patches for this are not possible due to the prior design of the Samba VFS layer, which used pathname-based calls for most meta-data operations.\nA two and a half year effort was undertaken to completely re-write the Samba VFS layer to stop the use of pathname-based calls in all cases involving reading and writing of metadata returned to the client. This work has finally been completed in Samba 4.15.0.\"", "threat_severity": "Moderate"}

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