mintupdate deadlocks on libpam-cap update due to pk-debconf-helper CPU spike

Describe the bug

The Update Manager (mintupdate) hangs indefinitely during the installation of the libpam-cap package. The background process pk-debconf-helper triggers a 100% CPU spike on a single core (C3 in my case). No interactive debconf dialog is presented to the user, causing a permanent hang of the GUI progress bar.

To Reproduce

• Launch Update Manager on Linux Mint 22.

• Select updates including libpam-cap.

• Start the update.

• The process stalls at "Preparing configuration for libpam-cap" (Preparazione dell'installazione di libpam-cap).

• Observe pk-debconf-helper consuming 100% CPU in terminal/btop.

Expected behavior

The Update Manager should display the required debconf interactive prompts (like the one for libpam-cap capabilities) or handle the configuration without deadlocking the CPU core.

Distribution

[x] Linux Mint Cinnamon 22.3 Zena

Software version

7.1.4

Logs

Plaintext:
2026-04-22 00:38:28 status half-installed libpam-cap:amd64 1:2.66-5ubuntu2.2
2026-04-22 00:38:30 status installed libpam-cap:amd64 1:2.66-5ubuntu2.4

Crash report

The application doesn't crash but becomes unresponsive. Manually killing the pk-debconf-helper process allows the update to proceed or be recovered via terminal using sudo dpkg --configure -a.

Additional context

The issue occurred on an iMac 2011 (i5-2400S). The system is Linux Mint 22. The deadlock seems to happen when a package requires an interactive configuration that the GUI fails to "pop up" to the user.

Locale

Plaintext:
LANG=it_IT.UTF-8
LANGUAGE=it
LC_CTYPE="it_IT.UTF-8"

Kernel version

6.17.0-22-generic

Start by reproducing the hang in Update Manager on Linux Mint 22.3 with an update including libpam-cap, while observing pk-debconf-helper and the GUI progress state. Compare the behavior when the helper is killed and dpkg is recovered, then determine what behavior is needed for the debconf prompt to appear or for installation to complete without the CPU spike.