All GNUTAR-based backups fail after the package update to1:3.5.1-8ubuntu1.1

Status changed to 'Confirmed' because the bug affects multiple users.

I've made a workaround for our environment by moving to the previously mentioned amgtar after finding this article that had some implementation examples:
https://serverfault.com/questions/915726/difference-between-amgtar-and-gnutar

It sounds like a better way moving forward now that I know about it.

These are my exact changes to amanda.conf as a diff

+ define application-tool app_amgtar {
+ plugin "amgtar"
+ }

...cut...

define dumptype server-encrypt {
    global
- program "GNUTAR"
+ program "APPLICATION"
+ application "app_amgtar"
     comment "dump with server symmetric encryption"
     compress none
+ estimate server
     encrypt server
    server_encrypt "/usr/sbin/amcrypt-ossl"
    server_decrypt_option "-d"
}

I also had to add this extra line to /etc/amanda-security.conf to allow the appropriate access
amgtar:gnutar_path=/usr/bin/tar

I haven't completed the backup to confirm its restore-ability yet but I'm no longer receiving the warnings.

Debian just released amanda 1:3.5.1-11 with the following:

Changes:
 amanda (1:3.5.1-11) unstable; urgency=medium
 .
   * d/p/49-fix-CVE-2022-37705_part_2: 48-fix-CVE-2022-37705 broken one use
     case at least, this patch fix it, fixing the following two bugs.
   * Bug fix: "backups fail with the following summary "FAILED [no
     backup size line]"", thanks to Norman Lyon (Closes: #1032330).
   * Bug fix: "Amanda is unusable", thanks to Kamil Jonca (Closes:
     #1032884).

So it would seem that the fix for the "no backup size line" line regression is found in https://sources.debian.org/src/amanda/1:3.5.1-11/debian/patches/49-fix-CVE-2022-37705_part_2/

Thank you for reporting this regression, and an extra thank you for also highlighting the fix. I will begin work on updating the effected packages.

This bug was fixed in the package amanda - 1:3.5.1-1ubuntu0.2

---------------
amanda (1:3.5.1-1ubuntu0.2) bionic-security; urgency=medium

  * SECURITY REGRESSION: Remove all patches from version 1:3.5.1-1ubuntu0.1
    getting the package back to the state of 1:3.5.1-1build2. Pending further
    investigation. (LP: #2012536)

 -- Eduardo Barretto <email address hidden> Thu, 23 Mar 2023 11:17:18 +0100

This bug was fixed in the package amanda - 1:3.5.1-9ubuntu0.2

---------------
amanda (1:3.5.1-9ubuntu0.2) kinetic-security; urgency=medium

  * SECURITY REGRESSION: Remove all patches from version 1:3.5.1-9ubuntu0.1
    getting the package back to the state of 1:3.5.1-9. Pending further
    investigation. (LP: #2012536)

 -- Eduardo Barretto <email address hidden> Thu, 23 Mar 2023 11:03:36 +0100

This bug was fixed in the package amanda - 1:3.5.1-2ubuntu0.2

---------------
amanda (1:3.5.1-2ubuntu0.2) focal-security; urgency=medium

  * SECURITY REGRESSION: Remove all patches from version 1:3.5.1-2ubuntu0.1
    getting the package back to the state of 1:3.5.1-2build3. Pending further
    investigation. (LP: #2012536)

 -- Eduardo Barretto <email address hidden> Thu, 23 Mar 2023 11:12:27 +0100

This bug was fixed in the package amanda - 1:3.5.1-8ubuntu1.2

---------------
amanda (1:3.5.1-8ubuntu1.2) jammy-security; urgency=medium

  * SECURITY REGRESSION: Remove all patches from version 1:3.5.1-8ubuntu1.1
    getting the package back to the state of 1:3.5.1-8ubuntu1.1. Pending further
    investigation. (LP: #2012536)

 -- Eduardo Barretto <email address hidden> Thu, 23 Mar 2023 11:06:24 +0100

We've reverted in the meantime all the patches that were applied in amanda. Dave will continue to investigate and re-patch those CVEs.
In the meantime sorry for the inconvenience.

Yesterday, I saw the same issue had been plaguing one of my backup clients since a few days (shame on me for not checking the backup logs daily).
I can confirm the update to 1:3.5.1-8ubuntu1.2 fixed the issue in Ubuntu 22.04.2 LTS.
Thanks for fixing!