{"schemaVersion":3,"id":"CVE-2018-6557","aliases":["UBUNTU-CVE-2018-6557","USN-3748-1"],"status":"published","duplicateOf":null,"title":null,"description":"The MOTD update script in the base-files package in Ubuntu 18.04 LTS before 10.1ubuntu2.2, and Ubuntu 18.10 before 10.1ubuntu6 incorrectly handled temporary files. A local attacker could use this issue to cause a denial of service, or possibly escalate privileges if kernel symlink restrictions were disabled.","dates":{"published":"2018-08-21T16:00:00.000Z","modified":"2024-09-16T18:24:32.413Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"NVD","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":7,"severity":"high","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","exploitability":null,"impact":null,"computed":false},{"version":"2.0","versionLabel":"v2.0","source":"NVD","score":4.4,"severity":"medium","vector":"AV:L/AC:M/Au:N/C:P/I:P/A:P","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":7,"severity":"high","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","exploitability":2.6,"impact":9.8,"computed":true},{"version":"3.0","versionLabel":"v3.0","source":"OSV · Ubuntu","score":7,"severity":"high","vector":"CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","exploitability":2.6,"impact":9.8,"computed":true}]},"epss":{"probability":0.00365,"percentile":0.28888,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.00365},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00365,"percentile":0.28888}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00365,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00365,"percentile":0.28888}]},"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":[],"exploitCount":0,"weaknesses":[{"id":"CWE-59","name":"Improper Link Resolution Before File Access ('Link Following')","description":"The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.","type":"weakness","status":"Draft","abstraction":"Base","likelihoodOfExploit":"Medium","url":"https://cwe.mitre.org/data/definitions/59.html"}],"affected":[{"vendor":"base-files_project","product":"base-files","name":"base-files","label":"base-files","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"10.1ubuntu2.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"10.1ubuntu2.2","eol":null,"hubHref":"/vendor/base-files_project/base-files"},{"vendor":"canonical","product":"ubuntu_linux","name":"ubuntu linux","label":"ubuntu_linux","ecosystem":null,"cpePart":"o","purl":null,"purlType":null,"versions":[{"text":"18.04","noFixRecorded":false,"fixedIn":null},{"text":"18.10","noFixRecorded":false,"fixedIn":null}],"versionsText":"18.04 | 18.10","eol":{"isEol":true,"eolDate":"2023-05-31T00:00:00.000Z","matchMethod":"cpe","cycle":{"name":"18.04","label":"18.04 'Bionic Beaver' (LTS)","eolFrom":"2023-05-31T00:00:00.000Z","isLts":true,"isMaintained":true,"latestVersion":"18.04.6"},"product":{"name":"ubuntu","label":"Ubuntu","category":"os"}},"hubHref":"/vendor/canonical/ubuntu_linux"},{"vendor":"ubuntu","product":"base-files","name":"base-files","label":"base-files","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/base-files","purlType":"deb","versions":[{"text":"< 10.1ubuntu2.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 10.1ubuntu2.2","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"base-files","name":"base-files","label":"base-files","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ unspecified, < 10.1ubuntu2.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ unspecified, < 10.1ubuntu2.2","eol":null,"hubHref":"/vendor/ubuntu/base-files"}],"affectedCount":4,"eol":{"hasEol":true,"count":1},"references":[{"url":"https://usn.ubuntu.com/3748-1/","label":"usn.ubuntu.com/3748-1/","hostname":"usn.ubuntu.com","tags":["Vendor Advisory","X Refsource UBUNTU"]},{"url":"http://www.securitytracker.com/id/1041530","label":"www.securitytracker.com/id/1041530","hostname":"www.securitytracker.com","tags":["VDB Entry","X Refsource SECTRACK","Broken Link","Third Party Advisory"]},{"url":"http://www.securityfocus.com/bid/105148","label":"www.securityfocus.com/bid/105148","hostname":"www.securityfocus.com","tags":["VDB Entry","X Refsource BID","Third Party Advisory"]},{"url":"https://ubuntu.com/security/CVE-2018-6557","label":"ubuntu.com/security/CVE-2018-6557","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"http://www.sbosnet.nl/","label":"www.sbosnet.nl","hostname":"www.sbosnet.nl","tags":["REPORT"]},{"url":"https://ubuntu.com/security/notices/USN-3748-1","label":"ubuntu.com/security/notices/USN-3748-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2018-6557","label":"www.cve.org/CVERecord?id=CVE-2018-6557","hostname":"www.cve.org","tags":["REPORT"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2018-08-21T16:00:00.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2024-09-16T18:24:32.413Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":28,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-19T15:53:20.389Z","stale":false,"partial":false}}