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Ubuntu Security Notice USN-5651-2
October 03, 2022

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

- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

strongSwan could be made do denial of service if it received
a specially crafted certificate.

Software Description:
- strongswan: IPsec VPN solution

Details:

USN-5651-1 fixed a vulnerability in strongSwan. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

 Lahav Schlesinger discovered that strongSwan incorrectly handled certain OCSP URIs and
 and CRL distribution points (CDP) in certificates. A remote attacker could
 possibly use this issue to initiate IKE_SAs and send crafted certificates
 that contain URIs pointing to servers under their control, which can lead
 to a denial-of-service attack.

Update instructions:

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

Ubuntu 16.04 ESM:
  libstrongswan                   5.3.5-1ubuntu3.8+esm3
  strongswan                      5.3.5-1ubuntu3.8+esm3

Ubuntu 14.04 ESM:
  libstrongswan                   5.1.2-0ubuntu2.11+esm3
  strongswan                      5.1.2-0ubuntu2.11+esm3

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

References:
  https://ubuntu.com/security/notices/USN-5651-2
  https://ubuntu.com/security/notices/USN-5651-1
  CVE-2022-40617