Description
Libreswan's pluto daemon has a use-after-free vulnerability when a client connecting using IKE over TCP closes the connection and another packet (retransmit or malicious) is received for the same tuple. IKE state is retained in memory after the client closes the connection, storing a pointer to iface_endpoint inside ike_sa.sa->st_iface_endpoint. Once this invalid pointer is used, the daemon crashes and restarts. This vulnerability can be triggered before the remote peer has authenticated itself. Continued exploitation can lead to a denial of service. Remote code execution could be possible. The IKE over TCP option is not enabled by default; only configurations that contain listen-tcp=yes are affected.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| The Libreswan Project | libreswan | 4.0 – ≤ 5.3.2, 5.4 – ≤ 5.4 | 5.3.3 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 13 | libreswan | No fix yet | — |
| Debian 12 | libreswan | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | libreswan | No fix yet | — |
| Ubuntu 26.04 LTS | libreswan | No fix yet | — |
| Ubuntu 24.04 LTS | libreswan | No fix yet | — |
| Ubuntu 22.04 LTS | libreswan | No fix yet | — |
| Ubuntu 20.04 LTS | libreswan | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | libreswan | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | libreswan +1 | 5.3.3-1.el10_2 | RHSA-2026:98088, RHSA-2026:89923 |
| RHEL 9 | libreswan | 4.15-11.el9_8 | RHSA-2026:98046, RHSA-2026:97878, RHSA-2026:89748 |
| RHEL 8 | libreswan | 4.12-2.el8_10.7 | RHSA-2026:90492 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | libreswan +1 | 5.3.3-1.el10_2 | ALSA-2026:89923 |
| AlmaLinux 9 | libreswan | 4.15-11.el9_8 | ALSA-2026:89748 |
| AlmaLinux 8 | libreswan | 4.12-2.el8_10.7 | ALSA-2026:90492 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | libreswan | 5.3.3-1.el10_2 | RLSA-2026:98088, RLSA-2026:89923 |
| Rocky Linux 10 | libreswan-minimal | 5.4.1-1.el10_3 | RLSA-2026:98088 |
| Rocky Linux 9 | libreswan | 4.15-11.el9_8 | RLSA-2026:97878, RLSA-2026:89748 |
| Rocky Linux 8 | libreswan | 4.12-2.el8_10.7 | RLSA-2026:90492 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | libreswan | 5.3.3-r0 | — |
| Alpine v3.23 | libreswan | 5.3.3-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | libreswan | 4.12-3.amzn2023.0.4 | ALAS2023-2026-3253 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | libreswan | 4.15-4 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | libreswan +1 | 5.3.3-1.0.1.el10_2 | ELSA-2026-89923 |
| Oracle Linux 9 | libreswan | 4.15-11.0.1.el9_8 | ELSA-2026-89748 |
| Oracle Linux 8 | libreswan | 4.12-2.0.1.el8_10.7 | ELSA-2026-90492 |
Advisories 19
- RHSA-2026:97878 Red Hat Security Advisory: libreswan security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:98088 Red Hat Security Advisory: libreswan security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:98046 Red Hat Security Advisory: libreswan security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:90492 Red Hat Security Advisory: libreswan security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:89923 Red Hat Security Advisory: libreswan security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:89748 Red Hat Security Advisory: libreswan security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RLSA-2026:98088 Important: libreswan security update Rocky Linux Security Advisories · Nov 13, 2026
- RLSA-2026:97878 Important: libreswan security update Rocky Linux Security Advisories · Nov 11, 2026
- WID-SEC-2026-4183 Red Hat Enterprise Linux Libreswan: Mehrere Schwachstellen ermöglichen Denial of Service BSI CERT-Bund (WID) · Nov 10, 2026
- RLSA-2026:90492 Important: libreswan security update Rocky Linux Security Advisories · Oct 29, 2026
- ALSA-2026:89748 Important: libreswan security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:89923 Important: libreswan security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:90492 Important: libreswan security update AlmaLinux Security Advisories · Oct 29, 2026
- RLSA-2026:89748 Important: libreswan security update Rocky Linux Security Advisories · Oct 27, 2026
- RLSA-2026:89923 Important: libreswan security update Rocky Linux Security Advisories · Oct 27, 2026
- ELSA-2026-90492 Important: libreswan security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 27, 2026
- ALAS2023-2026-3253 Important: libreswan security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 26, 2026
- ELSA-2026-89923 Important: libreswan security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Oct 26, 2026
- ELSA-2026-89748 Important: libreswan security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 26, 2026
References
- Libreswan Security Advisory CVE-2026-94453 vendor-advisory
- Libreswan CVE-2026-94453 Patches patch