CVE-2020-8516

Name: CVE-2020-8516
Creator: NVD / NIST
Published: 2020-02-02T13:15:10.903+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 2.57%

Last modified Jun 17, 2026

CVE-2020-8516 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. The daemon in Tor through 0.4.1.8 and 0.4.2.x through 0.4.2.6 does not verify that a rendezvous node is known before attempting to connect to it, which might make it easier for remote attackers to discover circuit information. NOTE: The network team of Tor claims this is an intended behavior and not a vulnerability. EPSS estimates a 2.57% chance of exploitation in the next 30 days.

Description

The daemon in Tor through 0.4.1.8 and 0.4.2.x through 0.4.2.6 does not verify that a rendezvous node is known before attempting to connect to it, which might make it easier for remote attackers to discover circuit information. NOTE: The network team of Tor claims this is an intended behavior and not a vulnerability

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS Probability

2.57%

83.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Torproject	Tor	<= 0.4.1.8
Torproject	Tor	>= 0.4.2.0, <= 0.4.2.6

References

https://lists.torproject.org/pipermail/tor-dev/2020-February/014146.htmlMailing List, Vendor Advisory
https://lists.torproject.org/pipermail/tor-dev/2020-February/014147.htmlMailing List, Vendor Advisory
https://security-tracker.debian.org/tracker/CVE-2020-8516Third Party Advisory
https://trac.torproject.org/projects/tor/ticket/33129Issue Tracking, Vendor Advisory
https://www.hackerfactor.com/blog/index.php?/archives/868-Deanonymizing-Tor-Circuits.htmlExploit, Mitigation, Technical Description, Third Party Advisory
https://lists.torproject.org/pipermail/tor-dev/2020-February/014146.htmlMailing List, Vendor Advisory
https://lists.torproject.org/pipermail/tor-dev/2020-February/014147.htmlMailing List, Vendor Advisory
https://security-tracker.debian.org/tracker/CVE-2020-8516Third Party Advisory
https://trac.torproject.org/projects/tor/ticket/33129Issue Tracking, Vendor Advisory
https://www.hackerfactor.com/blog/index.php?/archives/868-Deanonymizing-Tor-Circuits.htmlExploit, Mitigation, Technical Description, Third Party Advisory

Timeline

Published: Feb 2, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-8516?

How severe is CVE-2020-8516?

CVE-2020-8516 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 2.57% probability of exploitation in the next 30 days.

How do I fix CVE-2020-8516?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-8516?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST