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StrongswanApplication

CVE-2023-41913

CRITICAL · 9.8 CVSS v3.1 Published 2023-12-07
Fix available
A fix is available. Upgrade to 5.9.12 or later.
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 before 5.9.12 has a buffer overflow and possible unauthenticated remote code execution via a DH public value that exceeds the internal buffer in charon-tkm's DH proxy. The earliest affected version is 5.3.0. An attack can occur via a crafted IKE_SA_INIT message.

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 confidence

Buffer overflow vulnerability in strongSwan's charon-tkm daemon where a crafted IKE_SA_INIT message containing a Diffie-Hellman public value exceeding the internal buffer size leads to potential unauthenticated remote code execution. The vulnerability exists in the DH proxy functionality introduced in version 5.3.0.

MitigationUpgrade to strongSwan version 5.9.12 or later. Until patched, consider blocking IKE_SA_INIT messages at network perimeter or disabling charon-tkm if not required.

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:>= 5.3.0, < 5.9.12

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. Check installed strongSwan version
    Run 'ipsec --version' or check package manager (dpkg -l strongswan, rpm -q strongswan)
    Affected if Version is 5.3.0 or higher but below 5.9.12
  2. Verify if charon-tkm daemon is installed
    Check for charon-tkm binary: 'which charon-tkm' or 'ls /usr/lib/ipsec/charon-tkm'
    Affected if The charon-tkm binary exists on the system
  3. Determine if charon-tkm is enabled in strongSwan configuration
    Inspect /etc/strongswan.conf and /etc/strongswan.d/charon-tkm.conf for 'charon-tkm' loader entries, or check systemd service status with 'systemctl status charon-tkm'
    Affected if charon-tkm service is loaded/enabled or configured to start
  4. Check if charon-tkm process is running
    Run 'ps aux | grep charon-tkm' or check systemd 'systemctl status charon-tkm'
    Affected if charon-tkm process is actively running
  5. Verify IKE ports are accessible
    Check open ports: 'netstat -tulpn | grep 500' or 'ss -tulpn | grep 500' for UDP port 500 (IKE)
    Affected if UDP port 500 or port 4500 (IKE/NAT-T) is open and exposed to network

System is affected if strongSwan version is 5.3.0-5.9.11 AND charon-tkm daemon is enabled and running with IKE ports exposed.

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
Upgrade available Upgrade to 5.9.12 or later
Fixed in 5.9.12
Interim mitigation

Upgrade to strongSwan version 5.9.12 or later. Until patched, consider blocking IKE_SA_INIT messages at network perimeter or disabling charon-tkm if not required.

Recommended fix High confidence

strongSwan 5.9.12 or later

  1. Identify the current strongSwan version installed using 'strongswan --version' or 'ipsec --version'
  2. Stop the strongSwan service: 'systemctl stop strongswan' or 'service strongstrongswan stop'
  3. Upgrade strongSwan to version 5.9.12 or later using your distribution's package manager (e.g., 'apt-get install strongswan=5.9.12-1' or 'yum update strongswan' or 'dnf update strongswan')
  4. If using source compilation, download strongSwan 5.9.12 or later from www.strongswan.org and rebuild
  5. Verify the new version: 'strongswan --version' or 'ipsec --version'
  6. Restart the strongSwan service: 'systemctl start strongswan' or 'service strongswan start'
  7. Verify the charon-tkm daemon is running properly and no errors in logs

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

Fix this in Strongswan Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,770
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,832.

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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-2023-41913 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data