NULL pointer dereference in strongSwan - CVE-2026-35332

Vulnerability identifier: #VU151574

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-2026-35332

CWE-ID: CWE-476

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 a null-pointer dereference in libtls server-side ECDH public-value processing when handling an empty ECDH public value in a TLS client_key_exchange message before TLS 1.3. A remote attacker can send a specially crafted TLS client_key_exchange message to cause a denial of service.

The crash occurs when the TLS record ends immediately after the length byte for the empty public value.

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 6.0.6
libstrongswan (Ubuntu package) - addressed in versions 5.9.5-2ubuntu2.6, 5.9.13-2ubuntu4.24.04.3, 6.0.1-6ubuntu4.3
strongswan (Ubuntu package) - addressed in versions 5.9.5-2ubuntu2.6, 5.9.13-2ubuntu4.24.04.3, 6.0.1-6ubuntu4.3
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+deb12u4, 6.0.1-6+deb13u5

• https://www.strongswan.org/blog/2026/04/22/strongswan-vulnerability-(cve-2026-35332).html

• Multiple vulnerabilities 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