Elastic BeatsApplication · Elastic
CVE-2023-31421
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIt was discovered that when acting as TLS clients, Beats, Elastic Agent, APM Server, and Fleet Server did not verify whether the server certificate is valid for the target IP address; however, certificate signature validation is still performed. More specifically, when the client is configured to connect to an IP address (instead of a hostname) it does not validate the server certificate's IP SAN values against that IP address and certificate validation fails, and therefore the connection is not blocked as expected.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceWhen Beats, Elastic Agent, APM Server, or Fleet Server act as TLS clients and connect to a server using an IP address (instead of a hostname), they fail to validate that the server certificate's IP Subject Alternative Name (SAN) values match the target IP address. Certificate signature validation still works, but the IP SAN check is bypassed, allowing connections to servers presenting certificates not issued for that specific IP.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Elastic BeatsApplication
>= 8.0.0, <= 8.9.2
Elastic AgentApplication
>= 8.0.0, <= 8.9.2
Apm ServerApplication
>= 8.0.0, <= 8.9.2
Elastic Fleet ServerApplication
>= 8.0.0, <= 8.9.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Elastic product and versionRun the version command for the product: for Beats (filebeat, metricbeat, etc.) run 'product version', for Elastic Agent run 'elastic-agent version', for APM Server run 'apm-server version', or check the installed package version via system package managerAffected if Version is 8.0.0 through 8.9.2 inclusive, or if version cannot be determined but the product is known to be in the 8.x line before 8.9.3
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Determine if TLS connections use IP addressesReview TLS client configuration files (commonly in /etc/ for Beats, or the agent policy for Elastic Agent/Fleet Server) and look for 'hosts' or 'ssl' settings. Check whether the configured server endpoints use IP addresses (like https://192.168.1.1:9200) rather than hostnames (like https://hostname.example.com:9200)Affected if Any TLS client connection is configured to connect using an IP address instead of a hostname; if all connections use hostnames, the IP SAN validation bypass does not apply
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Verify SSL/TLS configuration is enabledInspect the SSL/TLS configuration block in the product config file. Look for 'ssl', 'tls', 'certificate', 'key', 'ca' settings under output or input sections that define TLS-encrypted connections to remote serversAffected if SSL/TLS is configured and active for outbound connections; if TLS is not in use, the vulnerability is not reachable
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Confirm connection target is using certificate-based TLSCheck the TLS configuration to verify the connection is to a server that presents an X.509 certificate (not mutual TLS with client cert only, not plaintext). Look for 'verification_mode', 'certificate_authorities', or 'ssl' settings indicating server certificate validation is expectedAffected if Server certificate validation is expected but the target is specified as an IP address, creating the condition where IP SAN matching is bypassed
You are affected if you have Elastic Beats, Elastic Agent, APM Server, or Fleet Server version 8.0.0-8.9.2 with TLS connections configured to servers using IP addresses instead of hostnames.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedEnsure TLS servers present certificates with IP SANs matching the target IP address, or update to patched versions of the affected products when released. Alternatively, connect using hostnames instead of IP addresses where standard hostname-based certificate validation is properly enforced.
8.9.3 or later (8.10.x, 8.11.x, or latest stable 8.x release)
- 1. Identify all Elastic Beats, Elastic Agent, APM Server, and Fleet Server instances running versions 8.0.0 through 8.9.2 in your environment
- 2. Plan an upgrade window following your organization's change management process
- 3. Upgrade Elastic Beats to version 8.9.3 or later
- 4. Upgrade Elastic Agent to version 8.9.3 or later
- 5. Upgrade APM Server to version 8.9.3 or later
- 6. Upgrade Elastic Fleet Server to version 8.9.3 or later
- 7. After upgrading, verify that TLS certificate validation for IP address connections is working correctly
- 8. Test a sample TLS connection to a server by IP address to confirm the fix validates IP SANs in the server certificate
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Elastic Beats
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,888.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-31421 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-31421 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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