{"schemaVersion":3,"id":"CVE-2021-39246","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"Tor Browser through 10.5.6 and 11.x through 11.0a4 allows a correlation attack that can compromise the privacy of visits to v2 onion addresses. Exact timestamps of these onion-service visits are logged locally, and an attacker might be able to compare them to timestamp data collected by the destination server (or collected by a rogue site within the Tor network).","dates":{"published":"2021-09-24T18:08:05.000Z","modified":"2024-08-04T02:06:42.498Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":6.1,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"NVD","vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":6.1,"severity":"medium","vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","exploitability":null,"impact":null,"computed":false},{"version":"2.0","versionLabel":"v2.0","source":"NVD","score":3.6,"severity":"low","vector":"AV:L/AC:L/Au:N/C:P/I:P/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00475,"percentile":0.39776,"severity":"low","asOf":"2026-10-20T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-20T00:00:00.000Z","baselineScore":0.00475},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00475,"percentile":0.39776}],"last30":[{"date":"2026-09-20T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00475,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00475,"percentile":0.39776}]},"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":"GITHUB_SICKCODES_SECURITY","name":"Security","source":"github","url":"https://github.com/sickcodes/security/blob/master/advisories/SICK-2020-001.md","maturity":"poc","reliabilityScore":0.3,"verified":false,"type":null,"platforms":[],"requiresAuth":null,"exploitdb":null,"metasploit":null},{"id":"REF_2EDFC796E29143BD","name":"Exploit Reference (sick.codes)","source":"reference","url":"https://sick.codes/sick-2021-111","maturity":"unknown","reliabilityScore":0.2,"verified":false,"type":null,"platforms":[],"requiresAuth":null,"exploitdb":null,"metasploit":null}],"exploitCount":2,"weaknesses":[{"id":"CWE-532","name":"Insertion of Sensitive Information into Log File","description":"The product writes sensitive information to a log file.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":"Medium","url":"https://cwe.mitre.org/data/definitions/532.html"}],"affected":[{"vendor":"torproject","product":"tor_browser","name":"tor browser","label":"tor_browser","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≤ 10.5.6","noFixRecorded":false,"fixedIn":null},{"text":"11.0:alpha2","noFixRecorded":false,"fixedIn":null},{"text":"11.0:alpha4","noFixRecorded":false,"fixedIn":null}],"versionsText":"≤ 10.5.6 | 11.0:alpha2 | 11.0:alpha4","eol":null,"hubHref":"/vendor/torproject/tor_browser"}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-111.md","label":"github.com/sickcodes/security/blob/master/advisories/SICK-2021-111.md","hostname":"github.com","tags":["X Refsource MISC","Exploit","Third Party Advisory"]},{"url":"https://sick.codes/sick-2021-111","label":"sick.codes/sick-2021-111","hostname":"sick.codes","tags":["X Refsource MISC","Exploit","Third Party Advisory"]},{"url":"https://www.privacyaffairs.com/cve-2021-39246-tor-vulnerability","label":"www.privacyaffairs.com/cve-2021-39246-tor-vulnerability","hostname":"www.privacyaffairs.com","tags":["X Refsource MISC","Third Party Advisory"]},{"url":"https://gitlab.torproject.org/tpo/core/tor/-/commit/80c404c4b79f3bcba3fc4585d4c62a62a04f3ed9","label":"gitlab.torproject.org/tpo/core/tor/-/commit/80c404c4b79f3bcba3fc4585d4c62a62a04f3ed9","hostname":"gitlab.torproject.org","tags":["X Refsource MISC","Patch","Vendor Advisory"]},{"url":"https://gitlab.torproject.org/tpo/core/tor/-/merge_requests/434","label":"gitlab.torproject.org/tpo/core/tor/-/merge_requests/434","hostname":"gitlab.torproject.org","tags":["X Refsource MISC","Vendor Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2021-09-24T18:08:05.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2024-08-04T02:06:42.498Z","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":"2026-10-21T06:56:54.665Z","stale":false,"partial":false}}