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CVE-2020-15572

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service ...

7.5 HighFix available

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor instances built to use Mozilla Network Security Services (NSS), aka TROVE-2020-001.

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
None
Integrity
None
Availability
High

Exploit likelihood

1.40%Up 0.6 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor instances built to use Mozilla Network Security Services (NSS), aka TROVE-2020-001.

Record
CVE-2020-15572
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:N/I:N/A:P
Weakness
CWE-125
Updated
2026-11-02
CVE List No score

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor instances built to use Mozilla Network Security Services (NSS), aka TROVE-2020-001.

Record
CVE-2020-15572
Updated
2026-11-02
EUVDEUVD-2020-7559 No score

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor instances built to use Mozilla Network Security Services (NSS), aka TROVE-2020-001.

Record
EUVD-2020-7559
Updated
2026-11-03
GitHub AdvisoriesGHSA-cfp9-244f-h66c No score

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service ...

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor instances built to use Mozilla Network Security Services (NSS), aka TROVE-2020-001.

Record
GHSA-cfp9-244f-h66c
Weakness
CWE-119
Updated
2026-11-02
OSV 7.5

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor instances built to use Mozilla Network Security Services (NSS), aka TROVE-2020-001.

Record
CVE-2020-15572
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2020-15572 7.5

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor instances built to use Mozilla Network Security Services (NSS), aka TROVE-2020-001.

Record
DEBIAN-CVE-2020-15572
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2020:1970-1 No score

Security update for tor

This update for tor fixes the following issues:

Updating tor to a newer version in the respective codestream.

  • tor 0.3.5.12:

    • Check channels+circuits on relays more thoroughly (TROVE-2020-005, boo#1178741)
    • Not affected by out-of-bound memory access (CVE-2020-15572, boo#1173979)
    • Fix DoS defenses on bridges with a pluggable transport
    • CVE-2020-10592: CPU consumption DoS and timing patterns (boo#1167013)
    • CVE-2020-10593: circuit padding memory leak (boo#1167014)

  • tor 0.4.4.6

    • Check channels+circuits on relays more thoroughly (TROVE-2020-005, boo#1178741)
    • Fix a crash due to an out-of-bound memory access (CVE-2020-15572, boo#1173979)
    • Fix logrotate to not fail when tor is stopped (boo#1164275)
Record
openSUSE-SU-2020:1970-1
Updated
2026-11-02
OSVopenSUSE-SU-2024:11469-1 No score

tor-0.4.6.7-2.2 on GA media

These are all security issues fixed in the tor-0.4.6.7-2.2 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:11469-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
tor
Debian:12
 before 0.4.3.6-1
0.4.3.6-1
tor
Debian:13
 before 0.4.3.6-1
0.4.3.6-1
tor
Debian:14
 before 0.4.3.6-1
0.4.3.6-1
tor
SUSE:Package Hub 12
From an advisory covering 3 CVEs
 before 0.4.4.6-bp152.2.3.1
0.4.4.6-bp152.2.3.1
tor
SUSE:Package Hub 15 SP1
From an advisory covering 3 CVEs
 before 0.4.4.6-bp152.2.3.1
0.4.4.6-bp152.2.3.1
tor
SUSE:Package Hub 15 SP2
From an advisory covering 3 CVEs
 before 0.4.4.6-bp152.2.3.1
0.4.4.6-bp152.2.3.1
tor
openSUSE:Leap 15.1
From an advisory covering 3 CVEs
 before 0.4.4.6-bp152.2.3.1
0.4.4.6-bp152.2.3.1
tor
openSUSE:Leap 15.2
From an advisory covering 3 CVEs
 before 0.4.4.6-bp152.2.3.1
0.4.4.6-bp152.2.3.1
tor
openSUSE:Tumbleweed
From an advisory covering 22 CVEs
 before 0.4.6.7-2.2
0.4.6.7-2.2

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-15572 is a high vulnerability (CVSS 7.5) in Torproject Tor, published July 15, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.40%, the 72nd percentile. Fixed in tor 0.4.3.6-1.

References

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