{"schemaVersion":3,"id":"CVE-2021-4138","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"Improved Host header checks to reject requests not sent to a well-known local hostname or IP, or the server-specified hostname.","dates":{"published":"2022-05-02T22:08:07.000Z","modified":"2024-08-03T17:16:04.258Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.3,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"NVD","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","exploitability":null,"impact":null,"computed":false},{"version":"2.0","versionLabel":"v2.0","source":"NVD","score":5,"severity":"medium","vector":"AV:N/AC:L/Au:N/C:N/I:P/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00847,"percentile":0.57383,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0.01299999999999999,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.00834},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00847,"percentile":0.57383}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00834,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00847,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00847,"percentile":0.57383}]},"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":[],"affected":[{"vendor":"mozilla","product":"geckodriver","name":"geckodriver","label":"geckodriver","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ unspecified, < 0.30.0","noFixRecorded":false,"fixedIn":null},{"text":"< 0.30.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ unspecified, < 0.30.0 | < 0.30.0","eol":null,"hubHref":"/vendor/mozilla/geckodriver"}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/mozilla/geckodriver/releases/tag/v0.30.0","label":"github.com/mozilla/geckodriver/releases/tag/v0.30.0","hostname":"github.com","tags":["X Refsource MISC","Release Notes","Third Party Advisory"]},{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1652612","label":"bugzilla.mozilla.org/show_bug.cgi?id=1652612","hostname":"bugzilla.mozilla.org","tags":["X Refsource MISC","Issue Tracking","Permissions Required","Third Party Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2022-05-02T22:08:07.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2024-08-03T17:16:04.258Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":21,"level":"low","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T11:50:38.650Z","stale":false,"partial":false}}