Hi, I don't understand the gory details, but I think the analysis comes from a trustworthy side and I'm forwarding it to get some visibility. I'm not sure it's directly backportable to stable either. Maybe there is a stable release branch for Perl 5.40 somewhere? There is an old opensource project called nfsen (https://github.com/phaag/nfsen) that is a framework around analysing netflow traffic data. It is a webfrontend written in PHP with a backend written in Perl. For a few years there have been reports about occasional crashes in a perl-based daemon on various distributions, including Debian. There have been wild speculations about the reasons, including hardware defects, attacks and cosmic rays. I have personally been affected since at least Bookworm. For trixie it looks like this. [679698.819796] [pango] fontcon[11953]: segfault at 4ac ip 000055618d88e978 sp 00007f84010be838 error 4 in perl[ae978,55618d824000+1ae000] likely on CPU 27 (core 5, socket 1) [915797.786633] [pango] fontcon[4158978]: segfault at 4ac ip 0000560f5914a978 sp 00007fe93e0cf838 error 4 in perl[ae978,560f590e0000+1ae000] likely on CPU 7 (core 3, socket 1) There has recently been a bug report on that on the rather new Github issue tracker (it used to be one of the few projects based on sf.net) that solicited a response from the author, pointing towards an upstream bug in perl that has been "recently" (as in: not yet in Debian stable) fixed. https://github.com/phaag/nfsen/issues/51#issuecomment-5729766748 | Thanks for your additional report. | | This appears to be a known Perl 5.40 issue rather than an nfsen bug. | | The analysis reveals: The crash occurs in Perl_csighandler3() when a | signal is delivered to a native thread created by Pango ([pango] | fontcon); that thread has no Perl interpreter context, resulting in the | characteristic NULL dereference at address 0x4ac. | | The issue is documented upstream as Perl GH #22487 and is fixed in Perl | 5.42, where such signals are redirected to the Perl main thread. Debian | Trixie, Ubuntu 26.04 and RHEL 10 all currently ship affected Perl 5.40.x | versions. Until the distributions backport the upstream fix, there is | unfortunately little that can reasonably be fixed inside nfsen itself. The upstream issue he is referencing to is https://github.com/Perl/perl5/issues/22487 . Bernhard