Authentication Bypass by Spoofing in strongSwan - CVE-2026-78134

Vulnerability identifier: #VU151584

CSH Severity: Low

CVSS v4: 7.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-78134

CWE-ID: CWE-290

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote user to bypass authorization controls by impersonating another user.

The vulnerability exists due to improper authentication of inner EAP identities in the eap-peap and eap-ttls plugins when processing tunneled EAP authentication. A remote user can authenticate with valid credentials while claiming another user's identity during the outer EAP-Identity exchange to bypass authorization controls by impersonating another user.

Exploitation requires the use of EAP-PEAP or EAP-TTLS tunneling authentication protocols.

strongSwan
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP5
Debian Linux
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Workstation Extension 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
SUSE Package Hub 15
Basesystem Module
openSUSE Leap
Ubuntu
strongswan-mysql
strongswan-nm-debuginfo
strongswan-sqlite-debuginfo
strongswan-nm
strongswan-sqlite
strongswan-mysql-debuginfo
strongswan-doc
strongswan-debugsource
strongswan-libs0
strongswan-hmac
strongswan-ipsec
strongswan
strongswan-debuginfo
strongswan-libs0-debuginfo
strongswan-ipsec-debuginfo
strongswan (Ubuntu package)
strongswan (Debian package)

Install security update from vendor's website.

strongSwan - update to 6.1.0
strongswan-mysql - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2
strongswan-nm-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-sqlite-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2
strongswan-nm - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-sqlite - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2
strongswan-mysql-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2
strongswan-doc - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-debugsource - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-libs0 - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-hmac - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-ipsec - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-libs0-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 5.9.14-150700.3.21.2
strongswan-ipsec-debuginfo - addressed in versions 5.9.11-150400.19.40.2, 5.9.11-150500.5.28.2, 5.9.12-150600.3.23.2, 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-2026-78134).html

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