CVE-2023-31421Network attack vector

TLS traffic interception via skipped IP SAN matching

Published Oct 26, 2023 · Updated Aug 2, 2024

Certificate validation failure in Beats, Elastic Agent, APM Server, and Fleet Server 8.0.0 through 8.9.2 allows attackers to intercept TLS traffic. When a client targets an IP address, its TLS verifier checks the certificate signature but fails to compare that address with the certificate's IP SAN entries. A network-positioned attacker still needs a certificate signed by a trusted authority, but can then read data sent through the accepted connection.

CVSS severity5.9
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Certificate validation failure in Beats, Elastic Agent, APM Server, and Fleet Server 8.0.0 through 8.9.2 allows attackers to intercept TLS traffic. When a client targets an IP address, its TLS verifier checks the certificate signature but fails to compare that address with the certificate's IP SAN entries. A network-positioned attacker still needs a certificate signed by a trusted authority, but can then read data sent through the accepted connection.

The record

CVE
CVE-2023-31421
Published
Oct 26, 2023
Updated
Aug 2, 2024
Vendor
Elastic
Product
Elastic Agent
Classifications
CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 26, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 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=8.0.0, 8.9.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Elastic · Elastic Agentversion=8.0.0, 8.9.2
Elastic · Fleet Serverversion=8.0.0, 8.9.2
Elastic · APM Serverversion=8.0.0, 8.9.2
Elastic · Beatsversion=8.0.0, 8.9.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.9ElasticCVSS:3.1/AV:N/AC:H/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-295Improper Certificate Validation
T1557Adversary-in-the-Middle

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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