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Ubuntu Security Notice USN-6488-2
December 14, 2023

strongswan vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS (Available with Ubuntu Pro)
- Ubuntu 16.04 LTS (Available with Ubuntu Pro)

Summary:

strongSwan could be made to crash or run programs if it received
specially crafted network traffic.

Software Description:
- strongswan: IPsec VPN solution

Details:

USN-6488-1 fixed a vulnerability in strongSwan. This update provides
the corresponding updates for Ubuntu 16.04 LTS and Ubuntu 18.04 LTS.

Original advisory details:

  Florian Picca discovered that strongSwan incorrectly handled certain DH
  public values. A remote attacker could use this issue to cause strongSwan
  to crash, resulting in a denial of service, or possibly execute arbitrary
  code.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 18.04 LTS (Available with Ubuntu Pro):
   libstrongswan                   5.6.2-1ubuntu2.9+esm1
   strongswan                       5.6.2-1ubuntu2.9+esm1

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
   libstrongswan                   5.3.5-1ubuntu3.8+esm4
   strongswan                       5.3.5-1ubuntu3.8+esm4

In general, a standard system update will make all the necessary changes.

References:
   https://ubuntu.com/security/notices/USN-6488-2
   https://ubuntu.com/security/notices/USN-6488-1
   CVE-2023-41913