Dovecot-pigeonhole version 2.4.2 used by Plesk Obsidian 18.0.76 causes dovecot to panic crash

[danami]

Username:

TITLE

Dovecot-pigeonhole version 2.4.2 used by Plesk Obsidian 18.0.76 causes dovecot to panic crash

PRODUCT, VERSION, OPERATING SYSTEM, ARCHITECTURE

Product version: Plesk Obsidian 18.0.76.1
OS version: Ubuntu 24.04 x86_64
Build date: 2026/02/18 09:00
Revision: f84108e33ae43d7bb0e6258488f707b39764d84f

PROBLEM DESCRIPTION

There is a known issue in the dovecot-pigeonhole v2.4.2 shipped with Plesk 18.0.76 related to how certain email clients handle message movement, particularly when the Sieve plugin is involved. The panic is often triggered by specific IMAP client behaviors, such as moving or deleting emails, especially from mobile devices like iPads or Android phones using apps like Thunderbird. The issue seems to stem from a conflict within the internal handling of the source mailbox during the Sieve-related operations. It has been widely discussed on the Dovecot mailing list and Plesk forums.

STEPS TO REPRODUCE

Upgrade to Plesk 18.0.76+ and you will see panics in your logs when the sieve plugin is used:

Feb 19 21:12:50 hosting dovecot: service=imap, user=user@domain, ip=[2a01:599:b2c:fd7c:5c44:12cd:c6c8:e118]. Error: Raw backtrace: libdovecot.so.0(backtrace_append+0x3e) [0x7ff251139fde] -> libdovecot.so.0(backtrace_get+0x22) [0x7ff25113a112] -> libdovecot.so.0(+0x14870e) [0x7ff25114870e] -> libdovecot.so.0(+0x1487b1) [0x7ff2511487b1] -> libdovecot.so.0(+0x6c296) [0x7ff25106c296] -> lib95_imap_sieve_plugin.so(+0x49df) [0x7ff2513c79df] -> lib95_imap_sieve_plugin.so(+0x7aab) [0x7ff2513caaab] -> libdovecot-storage.so.0(+0x657ee) [0x7ff2515477ee] -> libdovecot-storage.so.0(mailbox_save_alloc+0x79) [0x7ff25154bc59] -> imap(+0x17215) [0x561ca9779215] -> imap(command_exec+0x9c) [0x561ca9787d8c] -> imap(+0x23c92) [0x561ca9785c92] -> imap(+0x23d34) [0x561ca9785d34] -> imap(+0x23fbb) [0x561ca9785fbb] -> imap(client_handle_input+0x1c5) [0x561ca9786195] -> imap(client_input+0x73) [0x561ca9786743] -> libdovecot.so.0(io_loop_call_io+0x69) [0x7ff25115f319] -> libdovecot.so.0(io_loop_handler_run_internal+0x132) [0x7ff251160a02] -> libdovecot.so.0(io_loop_handler_run+0x50) [0x7ff25115f3c0] -> libdovecot.so.0(io_loop_run+0x40) [0x7ff25115f5a0] -> libdovecot.so.0(master_service_run+0xe8) [0x7ff2510afd18] -> imap(main+0x3fe) [0x561ca97769ee] -> libc.so.6(+0x2724a) [0x7ff250e4524a] -> libc.so.6(__libc_start_main+0x85) [0x7ff250e45305] -> imap(_start+0x21) [0x561ca9776ba1]

ACTUAL RESULT

Dovecot panics when using certain operations with the sieve plugin.

EXPECTED RESULT

Dovecot should not panic when using the sieve plugin.

ANY ADDITIONAL INFORMATION

Workaround
I've confirmed that the fix below will fix the issue:

// apply the fix
echo 'mail_attachment_detection_options =' > /etc/dovecot/conf.d/999_fix_crash.conf

// restart dovecot
systemctl restart dovecot

Dovecot 2.4.3 reverted the default for this setting to be empty to fix the issue:
All Settings | Dovecot CE

YOUR EXPECTATIONS FROM PLESK SERVICE TEAM

Confirm bug

 

[Sebahat.hadzhi]

Hi, @danami . Thank you for the report. There is already an existing internal case for the investigation of that issue. I will forward the details you added to it.