NULL pointer dereference in strongSwan - CVE-2026-35334

Vulnerability identifier: #VU151572

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-2026-35334

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 the gmp plugin's RSA decryption handling when processing an RSA ciphertext whose decryption result is zero. A remote attacker can send a crafted RSA ciphertext to cause a denial of service.

The condition can occur with an all-zero ciphertext or ciphertext that is a multiple of the RSA modulus.

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-2026-35334).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