{"cve":"CVE-2021-39246","nvd":{"published":"2021-09-24T19:15:07.147","modified":"2026-06-17T04:03:23.677","status":"Modified","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).","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","score":6.1},"cwes":["CWE-532"],"references":["https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-111.md","https://gitlab.torproject.org/tpo/core/tor/-/commit/80c404c4b79f3bcba3fc4585d4c62a62a04f3ed9","https://gitlab.torproject.org/tpo/core/tor/-/merge_requests/434","https://sick.codes/sick-2021-111","https://www.privacyaffairs.com/cve-2021-39246-tor-vulnerability"],"products":["torproject:tor_browser"],"source":"nvd","synced_at":"2026-10-19T21:23:41.316049955+00:00"},"epss":{"cve":"CVE-2021-39246","score":0.00475,"percentile":0.41086,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}