{"schemaVersion":3,"id":"CVE-2021-20251","aliases":["UBUNTU-CVE-2021-20251","DEBIAN-CVE-2021-20251","openSUSE-SU-2024:12435-1"],"status":"published","duplicateOf":null,"title":null,"description":"A flaw was found in samba. A race condition in the password lockout code may lead to the risk of brute force attacks being successful if special conditions are met.","dates":{"published":"2023-03-06T00:00:00.000Z","modified":"2025-03-06T15:49:56.099Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.9,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"NVD","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":5.9,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","exploitability":5.6,"impact":6,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Debian","score":5.9,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","exploitability":5.6,"impact":6,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":5.9,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00758,"percentile":0.54405,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.00758},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00758,"percentile":0.54405}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00758,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00758,"percentile":0.54405}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[{"id":"REF_D87F2C7A6CFBFF2F","name":"Exploit Reference (bugzilla.samba.org)","source":"reference","url":"https://bugzilla.samba.org/show_bug.cgi?id=14611","maturity":"unknown","reliabilityScore":0.2,"verified":false,"type":null,"platforms":[],"requiresAuth":null,"exploitdb":null,"metasploit":null}],"exploitCount":1,"weaknesses":[{"id":"CWE-362","name":"Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')","description":"The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.","type":"weakness","status":"Draft","abstraction":"Class","likelihoodOfExploit":"Medium","url":"https://cwe.mitre.org/data/definitions/362.html"}],"affected":[{"vendor":"debian","product":"samba","name":"samba","label":"samba","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/samba","purlType":"deb","versions":[{"text":"< 2:4.17.2+dfsg-3","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 2:4.17.2+dfsg-3","eol":{"isEol":null,"eolDate":null,"matchMethod":"name_exact","cycle":null,"product":{"name":"samba","label":"Samba","category":"server-app"}},"hubHref":null},{"vendor":"ubuntu","product":"samba","name":"samba","label":"samba","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/samba","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":{"isEol":null,"eolDate":null,"matchMethod":"name_exact","cycle":null,"product":{"name":"samba","label":"Samba","category":"server-app"}},"hubHref":null},{"vendor":"fedoraproject","product":"fedora","name":"fedora","label":"fedora","ecosystem":null,"cpePart":"o","purl":null,"purlType":null,"versions":[{"text":"37","noFixRecorded":false,"fixedIn":null}],"versionsText":"37","eol":{"isEol":true,"eolDate":"2023-12-05T00:00:00.000Z","matchMethod":"cpe","cycle":{"name":"37","label":"37","eolFrom":"2023-12-05T00:00:00.000Z","isLts":false,"isMaintained":false,"latestVersion":null},"product":{"name":"fedora","label":"Fedora Linux","category":"os"}},"hubHref":"/vendor/fedoraproject/fedora"},{"vendor":"opensuse","product":"samba&distro=openSUSE Tumbleweed","name":"samba","label":"samba&distro=openSUSE Tumbleweed","ecosystem":"openSUSE","cpePart":null,"purl":"pkg:rpm/opensuse/samba&distro=openSUSE Tumbleweed","purlType":"rpm","versions":[{"text":"< 4.17.1+git.270.17afe7cb6b-1.1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 4.17.1+git.270.17afe7cb6b-1.1","eol":{"isEol":null,"eolDate":null,"matchMethod":"name_exact","cycle":null,"product":{"name":"samba","label":"Samba","category":"server-app"}},"hubHref":null},{"vendor":"samba","product":"samba","name":"Samba","label":"samba","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 4.1.0, < 4.16.8","noFixRecorded":false,"fixedIn":null},{"text":"≥ 4.17.0, < 4.17.4","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 4.1.0, < 4.16.8 | ≥ 4.17.0, < 4.17.4","eol":{"isEol":null,"eolDate":null,"matchMethod":"name_exact","cycle":null,"product":{"name":"samba","label":"Samba","category":"server-app"}},"hubHref":"/vendor/samba/samba"}],"affectedCount":5,"eol":{"hasEol":true,"count":1},"references":[{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1929800","label":"bugzilla.redhat.com/show_bug.cgi?id=1929800","hostname":"bugzilla.redhat.com","tags":["Issue Tracking","Third Party Advisory"]},{"url":"https://bugzilla.samba.org/show_bug.cgi?id=14611","label":"bugzilla.samba.org/show_bug.cgi?id=14611","hostname":"bugzilla.samba.org","tags":["Exploit","Issue Tracking","Third Party Advisory"]},{"url":"https://security.netapp.com/advisory/ntap-20230331-0005/","label":"security.netapp.com/advisory/ntap-20230331-0005/","hostname":"security.netapp.com","tags":["Third Party Advisory"]},{"url":"https://security.gentoo.org/glsa/202309-06","label":"security.gentoo.org/glsa/202309-06","hostname":"security.gentoo.org","tags":["Vendor Advisory"]},{"url":"https://ubuntu.com/security/CVE-2021-20251","label":"ubuntu.com/security/CVE-2021-20251","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://gitlab.com/samba-team/samba/-/merge_requests/2708","label":"gitlab.com/samba-team/samba/-/merge_requests/2708","hostname":"gitlab.com","tags":["REPORT"]},{"url":"https://ubuntu.com/security/notices/USN-5822-1","label":"ubuntu.com/security/notices/USN-5822-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-20251","label":"www.cve.org/CVERecord?id=CVE-2021-20251","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2021-20251","label":"security-tracker.debian.org/tracker/CVE-2021-20251","hostname":"security-tracker.debian.org","tags":["Advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2021-20251","label":"www.suse.com/security/cve/CVE-2021-20251","hostname":"www.suse.com","tags":["WEB"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-20251","label":"nvd.nist.gov/vuln/detail/CVE-2021-20251","hostname":"nvd.nist.gov","tags":["Oval","Advisory"]}],"lineage":{"upstream":[],"downstream":["SUSE-SU-2023:0122-1","SUSE-SU-2023:0126-1","SUSE-SU-2023:0160-1","SUSE-SU-2023:0162-1","SUSE-SU-2023:0163-1","SUSE-SU-2023:0164-1","SUSE-SU-2023:0222-1","SUSE-SU-2023:0620-1","USN-5822-1"],"duplicates":[],"related":["SUSE-SU-2023:0122-1","SUSE-SU-2023:0126-1","SUSE-SU-2023:0160-1","SUSE-SU-2023:0162-1","SUSE-SU-2023:0163-1","SUSE-SU-2023:0164-1","SUSE-SU-2023:0222-1","SUSE-SU-2023:0620-1","USN-5822-1"]},"timeline":[{"kind":"published","date":"2023-03-06T00:00:00.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2025-03-06T15:49:56.099Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":34,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-19T15:50:11.235Z","stale":false,"partial":false}}