CVE-2020-15572

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.

Published: 2020-07-15 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-15572 is rated Moderate Risk (55/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.40%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-15572

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.51% 1.40% +0.90%
2 2025-03-30 0.80% 0.51% -0.30%
3 2025-03-29 — 0.80% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-15572

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2020-15572

OS Trackers for CVE-2020-15572

vendor priority summary link
alpine high CVE-2020-15572: 1 source package rows (tor); 8 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 8. https://security.alpinelinux.org/vuln/CVE-2020-15572
debian unimportant CVE-2020-15572 unimportant priority: Debian including 1 source packages (tor), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-15572
ubuntu negligible CVE-2020-15572 negligible priority: Ubuntu including 1 source packages (tor), 6 status rows across 6 suites (bionic, eoan, focal, trusty, upstream, xenial): not-affected 5, released 1. https://ubuntu.com/security/CVE-2020-15572

Affected software / configurations for CVE-2020-15572

Vendor Product Version Raw CPE
torproject tor < 0.3.5.11 cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*
torproject tor > 0.4.2.0, < 0.4.2.8 cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*
torproject tor > 0.4.3.0, < 0.4.3.6 cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*
torproject tor 0.4.4.0 cpe:2.3:a:torproject:tor:0.4.4.0:alpha:*:*:*:*:*:*
torproject tor 0.4.4.1 cpe:2.3:a:torproject:tor:0.4.4.1:alpha:*:*:*:*:*:*

References for CVE-2020-15572

cvelogic Threat Intelligence