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StrongswanApplication

CVE-2023-26463

CRITICAL · 9.8 CVSS v3.1 Published 2023-04-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
strongSwan 5.9.8 and 5.9.9 potentially allows remote code execution because it uses a variable named "public" for two different purposes within the same function. There is initially incorrect access control, later followed by an expired pointer dereference. One attack vector is sending an untrusted client certificate during EAP-TLS. A server is affected only if it loads plugins that implement TLS-based EAP methods (EAP-TLS, EAP-TTLS, EAP-PEAP, or EAP-TNC). This is fixed in 5.9.10.

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 · moderate confidence

strongSwan 5.9.8 and 5.9.9 contain a critical vulnerability where a variable named 'public' is reused for two different purposes within the same function, causing incorrect access control followed by an expired pointer dereference. This allows remote code execution by sending an untrusted client certificate during EAP-TLS authentication.

MitigationUpgrade to strongSwan 5.9.10 or later. If immediate upgrading is not feasible, disable plugins implementing TLS-based EAP methods (EAP-TLS, EAP-TTLS, EAP-PEAP, EAP-TNC) until the patch can be applied.

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
StrongswanApplication
Affected:= 5.9.8= 5.9.9

CVSS 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
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify strongSwan installation and version
    Run 'strongswan --version' or check the package manager (e.g., 'dpkg -l | grep strongswan', 'rpm -q strongswan')
    Affected if The installed version is exactly 5.9.8 or 5.9.9
  2. Confirm EAP-TLS or TLS-based EAP plugins are loaded
    Check the active plugins in strongSwan configuration (look in /etc/strongswan.conf, /etc/strongswan.d/, or run 'ipsec listall' to see loaded plugins)
    Affected if Plugins such as eap-tls, eap-ttls, eap-peap, or eap-tnc are enabled or loaded
  3. Verify IKEv2 connections using EAP-TLS authentication
    Inspect /etc/ipsec.conf and connections defined with 'eap=tls', 'eap=ttls', 'eap=peap', or 'eap=tnc'
    Affected if Any IKEv2 connection is configured to use TLS-based EAP authentication methods

You are affected if strongSwan version is 5.9.8 or 5.9.9 AND TLS-based EAP authentication (EAP-TLS, EAP-TTLS, EAP-PEAP, or EAP-TNC) is enabled or in use.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to strongSwan 5.9.10 or later. If immediate upgrading is not feasible, disable plugins implementing TLS-based EAP methods (EAP-TLS, EAP-TTLS, EAP-PEAP, EAP-TNC) until the patch can be applied.

Recommended fix High confidence

5.9.10

  1. 1. Identify the currently installed strongSwan version using 'strongswan -v' or 'ipsec --version'
  2. 2. Download strongSwan 5.9.10 from the official strongswan.org website or your distribution's package repository
  3. 3. If using a package manager, upgrade the strongswan package to version 5.9.10
  4. 4. If building from source, download strongswan-5.9.10.tar.gz, extract it, and follow the build instructions in the README
  5. 5. After upgrading, ensure the TLS-based EAP plugins (EAP-TLS, EAP-TTLS, EAP-PEAP, EAP-TNC) are properly configured if used
  6. 6. Restart the strongSwan daemon (ipsec stop && ipsec start) or reload the configuration
  7. 7. Verify the new version is running with 'strongswan -v' or 'ipsec --version'

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Strongswan Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-26463 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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