A PostSRSd security update has been released for Ubuntu 18.04 LTS.

USN-4730-1: PostSRSd vulnerability

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Ubuntu Security Notice USN-4730-1
February 10, 2021

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

- Ubuntu 18.04 LTS

Summary:

PostSRSd could be made to crash if it received specially crafted
input.

Software Description:
- postsrsd: Sender Rewriting Scheme via TCP-based lookup tables for Postfix

Details:

It was discovered that PostSRSd mishandled certain input. A remote attacker
could use this vulnerability to cause a denial of service via a long timestamp
tag in an SRS address.

Update instructions:

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

Ubuntu 18.04 LTS:
postsrsd 1.4-1ubuntu0.1

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

References:
  https://usn.ubuntu.com/4730-1
CVE-2020-35573

Package Information:
  https://launchpad.net/ubuntu/+source/postsrsd/1.4-1ubuntu0.1