CVE-2020-8516
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...
CVE-2020-8516 is a medium vulnerability (CVSS 5.3) in Torproject Tor, published February 2, 2020. Its validity is disputed. EPSS puts the chance of exploitation in the next 30 days at 2.50%, the 84th percentile.
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
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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
- Record
CVE-2020-8516- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Updated
- 2026-11-02
CVE List No score
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
- Record
CVE-2020-8516- Updated
- 2026-11-02
EUVDEUVD-2020-29382 No score
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
- Record
EUVD-2020-29382- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-gvvc-pv9r-rg5q
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...
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.
- Record
GHSA-gvvc-pv9r-rg5q- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
OSV
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
- Record
CVE-2020-8516- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
OSVDEBIAN-CVE-2020-8516
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
- Record
DEBIAN-CVE-2020-8516- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
torDebian:12 |
All versions, plus listed versions 0.4.7.13-10.4.7.16-10.4.8.10-10.4.8.10-1~bpo11+10.4.8.10-1~bpo12+1 Show 45 moreShow less0.4.8.11-10.4.8.11-1~bpo11+10.4.8.11-1~bpo12+10.4.8.12-10.4.8.12-1.10.4.8.12-1~bpo11+10.4.8.12-1~bpo12+10.4.8.13-10.4.8.13-20.4.8.13-2~bpo12+10.4.8.14-10.4.8.14-1~bpo12+10.4.8.16-10.4.8.21-10.4.8.21-1~bpo12+10.4.8.21-1~bpo13+10.4.8.21-1~bpo13+20.4.8.22-10.4.8.22-1~bpo12+10.4.8.22-1~bpo13+10.4.8.4-20.4.8.5-10.4.8.6-10.4.8.7-10.4.8.8-10.4.8.9-10.4.8.9-1~bpo11+10.4.8.9-1~bpo12+10.4.9.11-0+deb12u10.4.9.11-10.4.9.11-1~bpo13+10.4.9.12-20.4.9.12-30.4.9.12-40.4.9.13-10.4.9.14-10.4.9.5-10.4.9.5-20.4.9.5-2~bpo12+10.4.9.5-2~bpo13+10.4.9.6-0+deb12u10.4.9.6-10.4.9.6-1~bpo12+10.4.9.6-1~bpo13+10.4.9.8-0+deb12u1 |
None known |
torDebian:13 |
All versions, plus listed versions 0.4.8.16-10.4.8.21-10.4.8.21-1~bpo12+10.4.8.21-1~bpo13+10.4.8.21-1~bpo13+2 Show 29 moreShow less0.4.8.22-10.4.8.22-1~bpo12+10.4.8.22-1~bpo13+10.4.9.11-0+deb13u10.4.9.11-10.4.9.11-1~bpo13+10.4.9.12-0+deb13u10.4.9.12-0+deb13u20.4.9.12-20.4.9.12-30.4.9.12-40.4.9.13-0+deb13u10.4.9.13-10.4.9.14-0+deb13u10.4.9.14-10.4.9.5-10.4.9.5-20.4.9.5-2~bpo12+10.4.9.5-2~bpo13+10.4.9.6-0+deb13u10.4.9.6-10.4.9.6-1~bpo12+10.4.9.6-1~bpo13+10.4.9.8-0+deb13u10.4.9.8-10.4.9.8-1~bpo12+10.4.9.8-1~bpo13+10.4.9.9-10.4.9.9-1~bpo13+1 |
None known |
torDebian:14 |
All versions, plus listed versions 0.4.8.16-10.4.8.21-10.4.8.21-1~bpo12+10.4.8.21-1~bpo13+10.4.8.21-1~bpo13+2 Show 22 moreShow less0.4.8.22-10.4.8.22-1~bpo12+10.4.8.22-1~bpo13+10.4.9.11-10.4.9.11-1~bpo13+10.4.9.12-20.4.9.12-30.4.9.12-40.4.9.13-10.4.9.14-10.4.9.5-10.4.9.5-20.4.9.5-2~bpo12+10.4.9.5-2~bpo13+10.4.9.6-10.4.9.6-1~bpo12+10.4.9.6-1~bpo13+10.4.9.8-10.4.9.8-1~bpo12+10.4.9.8-1~bpo13+10.4.9.9-10.4.9.9-1~bpo13+1 |
None known |
History
| When | Changed | Sources |
|---|---|---|
| 2026-11-03 | aliases | EUVD |
| 2026-11-02 | created | CVE List, GitHub Advisories, NVD, OSV |
References
hackerfactor.com/blog/index.php?/archives/868-Deanonymizing-Tor-Circuits.html
lists.torproject.org/pipermail/tor-dev/2020-February/014147.html
security-tracker.debian.org/tracker/CVE-2020-8516
trac.torproject.org/projects/tor/ticket/33129
nvd.nist.gov/vuln/detail/CVE-2020-8516
github.com/advisories/GHSA-gvvc-pv9r-rg5q
Left out here: 5 versions. The JSON record has them.