CVE-2021-39246
Tor Browser through 10.5.6 and 11.x through 11.0a4 allows a correlation attack that can...
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).
Attack profile
How easy it is to exploit
- Attack vector
- Physical
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
6.1
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).
- Record
CVE-2021-39246- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - CVSS 2.0
- 3.6 Low
AV:L/AC:L/Au:N/C:P/I:P/A:N - Weakness
- CWE-532
- Updated
- 2026-11-02
CVE List No score
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).
- Record
CVE-2021-39246- Updated
- 2026-11-02
EUVDEUVD-2021-25608 No score
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).
- Record
EUVD-2021-25608- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-mqmf-5457-4f39 No score
Tor Browser through 10.5.6 and 11.x through 11.0a4 allows a correlation attack that can...
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).
- Record
GHSA-mqmf-5457-4f39- Weakness
- CWE-532
- Updated
- 2026-11-02
OSV
6.1
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).
- Record
CVE-2021-39246- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-39246 is a medium vulnerability (CVSS 6.1) in Torproject Tor Browser, published September 24, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.47%, the 41st percentile. No source names a fixed version.
References
github.com/sickcodes/security/blob/master/advisories/SICK-2021-111.md
sick.codes/sick-2021-111
privacyaffairs.com/cve-2021-39246-tor-vulnerability
gitlab.torproject.org/tpo/core/tor/-/commit/80c404c4b79f3bcba3fc4585d4c62a62a04f3ed9
gitlab.torproject.org/tpo/core/tor/-/merge_requests/434
nvd.nist.gov/vuln/detail/CVE-2021-39246
github.com/advisories/GHSA-mqmf-5457-4f39