CVE-2023-38711: An issue was discovered in Libreswan before 4.12

Routine

MEDIUM 6.5UPGRADE

CVE-2023-38711 is a medium-severity flaw (CVSS 6.5) affecting libreswan. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-476
Published	2023-08-25
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: libreswan

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-08-25 21:15 UTCPublished CVE record published
2026-06-17 06:11 UTCUpdated Record last modified

libreswan libreswan UPGRADE

Affected: >= 4.6 and < 4.12

Fixed in: 4.12

Safe to downgrade to: a release before 4.6

1. Check installed version

apt-cache policy libreswan || rpm -q libreswan || libreswan --version

2. UPGRADE to 4.12 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libreswan

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libreswan

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.6 (Debian / Ubuntu)

apt-cache madison libreswan sudo apt install libreswan=<VERSION_BEFORE_4.6> sudo apt-mark hold libreswan

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libreswan sudo dnf downgrade libreswan-<VERSION_BEFORE_4.6> sudo dnf versionlock add libreswan

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-38711?

libreswan: upgrade to 4.12. Exact commands for each OS are on this page.

Is CVE-2023-38711 being exploited?

CVE-2023-38711 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-38711 affect?

CVE-2023-38711 affects libreswan. Severity is medium (CVSS 6.5). 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 dae

How urgent is CVE-2023-38711?

Priority 37/100. No elevated risk signals yet.

Related CVEs

CVE-2026-12413 HIGH 7.5 UPGRADE An invalidly formatted IKEv2 fragment causes the Libreswan pluto daemon to crash and restart
CVE-2026-50721 HIGH 8.1 UPGRADE Libreswan, via the function RSA_authenticate_hash_signature_raw_rsa(), did not correctly verify the length of
CVE-2026-50722 HIGH 8.1 UPGRADE Libreswan, via the function RSA_authenticate_hash_signature_pkcs1_1_5_rsa(), did not correctly verify the DER
CVE-2024-3652 MEDIUM 6.5 UPGRADE The Libreswan Project was notified of an issue causing libreswan to restart when using IKEv1 without specifyin
CVE-2023-38712 MEDIUM 6.5 UPGRADE An issue was discovered in Libreswan 3.x and 4.x before 4.12

References

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