CVE-2020-36400

ZeroMQ libzmq 4.3.3 has a heap-based buffer overflow in zmq::tcp_read, a different vulnerability than CVE-2021-20235.

Published: 2021-07-01 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-36400 is rated Moderate Risk (60.8/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 0.54%). 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-2020-36400

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 2025-03-30 1.70% 0.54% -1.16%
2 2025-03-29 0.54% 1.70% +1.16%
3 2025-03-17 — 0.54% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-36400

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2020-36400

OS Trackers for CVE-2020-36400

vendor priority summary link
debian unimportant CVE-2020-36400 unimportant priority: Debian including 1 source packages (zeromq3), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-36400
redhat high — https://access.redhat.com/security/cve/CVE-2020-36400
suse critical CVE-2020-36400 severity critical: SUSE including 5 source package names (libzmq3, libzmq5, libzmq5-32bit, zeromq, zeromq-devel), 46 product×package rows across 20 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 6, … (20 product lines)): Known Not Affected 46. https://www.suse.com/security/cve/CVE-2020-36400/
ubuntu medium CVE-2020-36400 medium priority: Ubuntu including 1 source packages (zeromq3), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): not-affected 9. https://ubuntu.com/security/CVE-2020-36400

Affected software / configurations for CVE-2020-36400

Vendor Product Version Raw CPE
zeromq libzmq 4.3.3 cpe:2.3:a:zeromq:libzmq:4.3.3:*:*:*:*:*:*:*

References for CVE-2020-36400

cvelogic Threat Intelligence