Improper Authentication in strongSwan - CVE-2026-78135

Vulnerability identifier: #VU151583

CSH Severity: Medium

CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-78135

CWE-ID: CWE-287

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to establish a usable Child SA before authentication completes.

The vulnerability exists due to improper state validation in libcharon's task manager when processing CREATE_CHILD_SA requests on unestablished IKE SAs. A remote attacker can send a CREATE_CHILD_SA request during EAP authentication to establish a usable Child SA before authentication completes.

Exploitation requires EAP authentication and either no configured IP address pool or an explicit remote traffic selector.

strongSwan
SUSE Linux Enterprise Server 15 SP4
Debian Linux
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Workstation Extension 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
SUSE Package Hub 15
Basesystem Module
openSUSE Leap
Ubuntu
strongswan-ipsec-debuginfo
strongswan-mysql
strongswan-nm-debuginfo
strongswan-sqlite-debuginfo
strongswan-nm
strongswan-sqlite
strongswan-mysql-debuginfo
strongswan-doc
strongswan-libs0
strongswan-hmac
strongswan-ipsec
strongswan
strongswan-debuginfo
strongswan-libs0-debuginfo
strongswan-debugsource
strongswan (Ubuntu package)
strongswan (Debian package)

Install security update from vendor's website.

strongSwan - update to 6.1.0
strongswan-ipsec-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-mysql - update to 5.9.11-150400.19.40.2
strongswan-nm-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-sqlite-debuginfo - update to 5.9.11-150400.19.40.2
strongswan-nm - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-sqlite - update to 5.9.11-150400.19.40.2
strongswan-mysql-debuginfo - update to 5.9.11-150400.19.40.2
strongswan-doc - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-libs0 - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-hmac - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-ipsec - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-libs0-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan-debugsource - addressed in versions 5.9.11-150400.19.40.2, 5.9.14-150700.3.21.2
strongswan (Ubuntu package) - addressed in versions 5.9.5-2ubuntu2.8, 5.9.13-2ubuntu4.24.04.5, 6.0.4-1ubuntu3.2
strongswan (Debian package) - update to 6.0.1-6+deb13u7

• https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78135).html

• Multiple vulnerabilities in strongSwan
• Debian update for strongswan
• SUSE update for strongswan
• Ubuntu update for strongswan
• SUSE update for strongswan