How severe is CVE-2020-4067?

CVE-2020-4067 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability low.

Is CVE-2020-4067 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-4067?

CVE-2020-4067 primarily affects Coturn Project Coturn. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-4067?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-4067 published?

CVE-2020-4067 was published on 2020-06-29 and last updated on 2026-06-17.

CVE-2020-4067

CVE-2020-4067 is a high-severity vulnerability in Coturn Project Coturn with a CVSS 3.x base score of 7.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-665.

Key facts

Severity: High (CVSS 3.x base score 7.0)
CVSS v2: 5.0
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-665
Affected product: Coturn Project Coturn
Published: 2020-06-29
Last modified: 2026-06-17

Description

In coturn before version 4.5.1.3, there is an issue whereby STUN/TURN response buffer is not initialized properly. There is a leak of information between different client connections. One client (an attacker) could use their connection to intelligently query coturn to get interesting bytes in the padding bytes from the connection of another client. This has been fixed in 4.5.1.3.

Frequently asked questions

What is CVE-2020-4067?: In coturn before version 4.5.1.3, there is an issue whereby STUN/TURN response buffer is not initialized properly. There is a leak of information between different client connections. One client (an attacker) could use their connection to intelligently query coturn to get interesting bytes in the padding bytes from the connection of another client. This has been fixed in 4.5.1.3.
How severe is CVE-2020-4067?: CVE-2020-4067 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability low.
Is CVE-2020-4067 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-4067?: CVE-2020-4067 primarily affects Coturn Project Coturn. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-4067?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-4067 published?: CVE-2020-4067 was published on 2020-06-29 and last updated on 2026-06-17.

References

Affected products (11)

cpe:2.3:a:coturn_project:coturn:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*

More vulnerabilities in Coturn Project Coturn

CVE-2020-6061 — Critical (CVSS 9.8): An exploitable heap out-of-bounds read vulnerability exists in the way CoTURN 4.5.1.1 web server parses POST requests.…
CVE-2018-4059 — Critical (CVSS 9.8): An exploitable unsafe default configuration vulnerability exists in the TURN server function of coTURN prior to version…
CVE-2018-4056 — Critical (CVSS 9.8): An exploitable SQL injection vulnerability exists in the administrator web portal function of coTURN prior to version…
CVE-2026-43994 — High (CVSS 8.1): Coturn is a free open source implementation of TURN and STUN Server. Versions prior to 4.10.0 contain a stack buffer…
CVE-2018-4058 — High (CVSS 7.7): An exploitable unsafe default configuration vulnerability exists in the TURN server functionality of coTURN prior to…
CVE-2026-40613 — High (CVSS 7.5): Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.10.0, the STUN/TURN attribute parsing…

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