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LibreswanApplication

CVE-2023-38711

MEDIUM · 6.5 CVSS v3.1 Published 2023-08-25
Fix available
A fix is available. Upgrade to 4.12 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable 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
An issue was discovered in Libreswan before 4.12. When an IKEv1 Quick Mode connection configured with ID_IPV4_ADDR or ID_IPV6_ADDR receives an IDcr payload with ID_FQDN, a NULL pointer dereference causes a crash and restart of the pluto daemon. NOTE: the earliest affected version is 4.6.

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

Libreswan before version 4.12 contains a NULL pointer dereference in the pluto IKE daemon. When an IKEv1 Quick Mode connection is configured to expect an IPv4 or IPv6 address ID (ID_IPV4_ADDR/ID_IPV6_ADDR) but receives an IDcr payload containing an ID_FQDN (Fully Qualified Domain Name), the daemon attempts to process the FQDN as an IP address, resulting in a NULL dereference crash and restart of the pluto daemon.

MitigationUpgrade to Libreswan 4.12 or later. If immediate upgrade is not feasible, restrict IKEv1 Quick Mode peer connections to trusted sources to prevent malicious ID type mismatches from triggering the crash.

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
LibreswanApplication
Affected:>= 4.6, < 4.12

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 Libreswan version
    Run 'ipsec --version' or 'rpm -q libreswan' (RHEL) or 'dpkg -l libreswan' (Debian) to retrieve the installed version number
    Affected if The installed version is 4.6 or higher but lower than 4.12
  2. Verify IKEv1 Quick Mode connections exist
    Review /etc/ipsec.conf and files in /etc/ipsec.d/ for 'phase2=esp' or 'phase2alg' configurations, which indicate IKEv1 Quick Mode. Also check for 'ikev1=...' directives
    Affected if Any IKEv1 Quick Mode (phase2) connections are configured using Libreswan
  3. Identify connections expecting IPv4/IPv6 address IDs
    Search configuration files for 'leftid=ip' or 'rightid=ip' directives, or look for connections using ID_IPV4_ADDR/ID_IPV6_ADDR ID types. These indicate the connection expects an IP address ID
    Affected if Any IKEv1 Quick Mode connection is configured to expect an IPv4 or IPv6 address ID (ID_IPV4_ADDR/ID_IPV6_ADDR)
  4. Confirm pluto daemon is running and reachable
    Run 'ipsec status' or check if the pluto process is running via 'ps aux | grep pluto'
    Affected if The pluto daemon is active and processing IKE connections

A user is affected if Libreswan version is between 4.6 and 4.11 inclusive AND they have IKEv1 Quick Mode connections configured to expect IPv4/IPv6 address IDs, with the pluto daemon actively running.

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 4.12 or later
Fixed in 4.12
Interim mitigation

Upgrade to Libreswan 4.12 or later. If immediate upgrade is not feasible, restrict IKEv1 Quick Mode peer connections to trusted sources to prevent malicious ID type mismatches from triggering the crash.

Recommended fix High confidence

Libreswan 4.12 or later

  1. Check current installed Libreswan version using 'ipsec --version' or package manager
  2. Backup current configuration files in /etc/ipsec.d/ and /etc/ipsec.conf
  3. Download Libreswan 4.12 or later from the official source (downloads.libreswan.org or GitHub releases)
  4. Extract the source package if downloading source code
  5. For source installations: Run './configure && make && make install' as root or via sudo
  6. For package manager systems: Install the downloaded package using your distro's package manager (e.g., 'dpkg -i' or 'rpm -U')
  7. Verify the new version is installed using 'ipsec --version'
  8. Restart the ipsec service using 'systemctl restart ipsec' or 'service ipsec restart'
Caveat Review release notes for any configuration or behavioral changes between your current version and 4.12; test in staging environment before production deployment

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

Fix this in Libreswan Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

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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-2023-38711 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