{"id":"CVE-2021-39246","aliases":["EUVD-2021-25608","GHSA-mqmf-5457-4f39"],"status":"published","title":"Tor Browser through 10.5.6 and 11.x through 11.0a4 allows a correlation attack that can...","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).","severity":{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-12","score":0.00475,"percentile":0.4156,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-532"],"published":"2021-09-24T18:08:05Z","modified":"2026-06-17T04:03:23Z","products":[{"vendor":"torproject","product":"tor_browser"}],"references":[{"url":"https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-111.md","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory","evidence"]},{"url":"https://sick.codes/sick-2021-111","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory","evidence"]},{"url":"https://www.privacyaffairs.com/cve-2021-39246-tor-vulnerability","tags":["x_refsource_MISC","x_transferred","Third Party Advisory","advisory"]},{"url":"https://gitlab.torproject.org/tpo/core/tor/-/commit/80c404c4b79f3bcba3fc4585d4c62a62a04f3ed9","tags":["x_refsource_MISC","x_transferred","Patch","Vendor Advisory","fix"]},{"url":"https://gitlab.torproject.org/tpo/core/tor/-/merge_requests/434","tags":["x_refsource_MISC","x_transferred","Vendor Advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-39246"},{"url":"https://github.com/advisories/GHSA-mqmf-5457-4f39"}],"sources":{"cve":[{"id":"CVE-2021-39246","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).","status":"published","published":"2021-09-24T18:08:05Z","modified":"2024-08-04T02:06:42.498Z","updated_at":"2026-11-02T14:33:09.864034Z"}],"euvd":[{"id":"EUVD-2021-25608","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).","status":"published","published":"2021-09-24T18:08:05Z","modified":"2024-08-04T02:06:42Z","updated_at":"2026-11-03T03:24:23.719378Z"}],"ghsa":[{"id":"GHSA-mqmf-5457-4f39","title":"Tor Browser through 10.5.6 and 11.x through 11.0a4 allows a correlation attack that can...","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. If --log or --verbose is used, 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).","status":"published","published":"2022-05-24T19:15:41Z","modified":"2023-01-30T05:02:27Z","cwes":["CWE-532"],"updated_at":"2026-11-02T14:46:38.51672Z"}],"nvd":[{"id":"CVE-2021-39246","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).","status":"published","published":"2021-09-24T19:15:07.147Z","modified":"2026-06-17T04:03:23.677Z","cvss":[{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"medium","assessor":"primary"},{"version":"2.0","score":3.6,"vector":"AV:L/AC:L/Au:N/C:P/I:P/A:N","level":"low","assessor":"primary"}],"cwes":["CWE-532"],"updated_at":"2026-11-02T14:06:58.933037Z"}],"osv":[{"id":"CVE-2021-39246","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).","status":"published","published":"2021-09-24T19:15:07.147Z","modified":"2026-04-11T21:23:18.225502Z","cvss":[{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T15:44:20.843843Z"}]}}