Vulnerability Monitor

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CVE-2021-39246

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).

Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.1, with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), for affected systems. Impacting 4 products from torproject, from apple, from linux and 1 other, organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2021-09-24T19:15:07.147

Last Modified

2024-11-21T06:19:00.780

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 6.1 (MEDIUM)

CVSSv2 Vector

AV:L/AC:L/Au:N/C:P/I:P/A:N

Access Vector: LOCAL
Access Complexity: LOW
Authentication: NONE
Confidentiality Impact: PARTIAL
Integrity Impact: PARTIAL
Availability Impact: NONE

Exploitability Score

3.9

Impact Score

4.9

Weaknesses

Type: Primary
CWE-532

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	torproject	tor_browser	≤ 10.5.6	Yes
Application	torproject	tor_browser	11.0	Yes
Application	torproject	tor_browser	11.0	Yes
Operating System	apple	macos	-	No
Operating System	linux	linux_kernel	-	No
Operating System	microsoft	windows	-	No

References

https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-111.md Exploit, Third Party Advisory ([email protected])
https://gitlab.torproject.org/tpo/core/tor/-/commit/80c404c4b79f3bcba3fc4585d4c62a62a04f3ed9 Patch, Vendor Advisory ([email protected])
https://gitlab.torproject.org/tpo/core/tor/-/merge_requests/434 Vendor Advisory ([email protected])
https://sick.codes/sick-2021-111 Exploit, Third Party Advisory ([email protected])
https://www.privacyaffairs.com/cve-2021-39246-tor-vulnerability Third Party Advisory ([email protected])
https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-111.md Exploit, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://gitlab.torproject.org/tpo/core/tor/-/commit/80c404c4b79f3bcba3fc4585d4c62a62a04f3ed9 Patch, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://gitlab.torproject.org/tpo/core/tor/-/merge_requests/434 Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://sick.codes/sick-2021-111 Exploit, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.privacyaffairs.com/cve-2021-39246-tor-vulnerability Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For torproject's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.