CVE-2020-17516Network attack vector

Internode mTLS bypass via plaintext connection acceptance

Published Feb 3, 2021 · Updated Aug 4, 2024

Authentication bypass in Apache Cassandra allows remote attackers to bypass mutual TLS and establish unencrypted internode connections. The inbound internode listener accepts plaintext when server_encryption_options.internode_encryption is dc or rack instead of enforcing TLS according to peer topology. Exploitation requires network access to the internode service and one of those settings; published assessments identify confidentiality impact only.

CVSS severity7.5
High
EPSS probability1.93%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Apache Cassandra allows remote attackers to bypass mutual TLS and establish unencrypted internode connections. The inbound internode listener accepts plaintext when server_encryption_options.internode_encryption is dc or rack instead of enforcing TLS according to peer topology. Exploitation requires network access to the internode service and one of those settings; published assessments identify confidentiality impact only.

The record

CVE
CVE-2020-17516
Published
Feb 3, 2021
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Cassandra
Classifications
CWE-290, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 3, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.1.0 to 2.1.22
  2. Affected versionversion=2.2.0 to 2.2.19
  3. Affected versionversion=3.0.0 to 3.0.23
  4. Affected versionversion=3.11.0 to 3.11.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Cassandraversion=2.1.0 to 2.1.22; version=2.2.0 to 2.2.19; version=3.0.0 to 3.0.23; version=3.11.0 to 3.11.9

Published CVSS scores

5.9SUSECVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
4.3National Vulnerability DatabaseAV:N/AC:M/Au:N/C:P/I:N/A:N
7.5National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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