Integer underflow in strongSwan - CVE-2026-25075

Vulnerability identifier: #VU151571

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-25075

CWE-ID: CWE-191

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to an integer underflow in the eap-ttls plugin when processing EAP-TTLS attribute-value pairs. A remote attacker can send a crafted EAP-TTLS message to cause a denial of service.

strongSwan
Debian Linux
Fedora
Ubuntu
libstrongswan (Ubuntu package)
strongswan (Ubuntu package)
strongswan
strongswan (Debian package)

Install security update from vendor's website.

strongSwan - update to 6.0.5
libstrongswan (Ubuntu package) - addressed in versions 5.9.5-2ubuntu2.5, 5.9.13-2ubuntu4.24.04.2, 6.0.1-6ubuntu4.2
strongswan (Ubuntu package) - addressed in versions 5.9.5-2ubuntu2.5, 5.9.13-2ubuntu4.24.04.2, 6.0.1-6ubuntu4.2
strongswan - addressed in versions 6.0.6-1.el8, 6.0.6-1.el9, 6.0.6-1.el10_3, 6.0.6-2.fc44, 6.0.6-3.fc43, 6.0.7-2.fc43
strongswan (Debian package) - addressed in versions 5.9.8-5+deb12u3, 6.0.1-6+deb13u4

• https://www.strongswan.org/blog/2026/03/23/strongswan-vulnerability-(cve-2026-25075).html

• Integer underflow in strongSwan
• Debian update for strongswan
• Fedora 44 update for strongswan
• Fedora 43 update for strongswan
• Fedora EPEL 10.3 update for strongswan
• Fedora EPEL 9 update for strongswan
• Fedora EPEL 8 update for strongswan
• Fedora 43 update for strongswan
• Ubuntu update for strongswan