PERL5241DELTA(1)

🎀 perl5241delta — what's new for perl v5.24.1 🎀

okay bestie, welcome to perl5241delta(1) — this is the page where we spill all the tea about what changed between one perl release and the next. no cap, it's shorter than you'd think, but every crumb matters 💅

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🌸 DESCRIPTION 🌸

This document describes differences between the 5.24.0 release and the 5.24.1 release.

Real talk though — if you're upgrading from something older, like 5.22.0, you gotta go read perl5240delta first, because that one walks you through the differences between 5.22.0 and 5.24.0. Don't skip it, bestie, it's giving prerequisite energy 📚✨

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🔥 Security 🔥

🔒 -Di switch is now required for PerlIO debugging output 🔒

okay so previously PerlIO debugging output would just get yeeted into whatever file the PERLIO_DEBUG environment variable named — that is, if perl wasn't running setuid and the -T or -t switches hadn't been parsed yet. 🫠

and the way that mattered: if perl did output at a point where it hadn't yet parsed its switches, that could result in perl creating or overwriting the file named by PERLIO_DEBUG — even when the -T switch had been supplied. like, the whole point of -T is taint mode and it just... didn't save you here 😭

Perl now requires the -Di switch to produce PerlIO debugging output. By default this is written to stderr, but can optionally be redirected to a file by setting the PERLIO_DEBUG environment variable.

and if perl is running setuid or the -T switch was supplied? then PERLIO_DEBUG is ignored and the debugging output is sent to stderr as for any other -D switch. security said nope, we're not doing that anymore 💀✋

🔒 Core modules and tools no longer search "." for optional modules 🔒

The tools and many modules supplied in core no longer search the default current directory entry in @INC for optional modules. For example, Storable will remove the final . from @INC before trying to load Log::Agent.

why tho? because this prevents an attacker injecting an optional module into a process run by another user where the current directory is writable by the attacker — e.g. the /tmp directory. classic villain behavior, honestly 🙈

In most cases this removal should not cause problems, but difficulties were encountered with base, which treats every module name supplied as optional. These difficulties have not yet been resolved, so for this release there are no changes to base. We hope to have a fix for base in Perl 5.24.2. fingers crossed fr fr 🤞

now — to protect your own code from this attack, either remove the default . entry from @INC at the start of your script, so:

#!/usr/bin/perl
use strict;
...

becomes:

#!/usr/bin/perl
BEGIN { pop @INC if $INC[-1] eq '.' }
use strict;
...

or, for modules, remove . from a localized @INC, so:

my $can_foo = eval { require Foo; }

becomes:

my $can_foo = eval {
    local @INC = @INC;
    pop @INC if $INC[-1] eq '.';
    require Foo;
};

look at that glow-up ✨ so clean, so safe 💖

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💥 Incompatible Changes 💥

Other than the security changes above there are no changes intentionally incompatible with Perl 5.24.0. If any exist, they are bugs, and we request that you submit a report. See "Reporting Bugs" below. 👀

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📦 Modules and Pragmata 📦

🦋 Updated Modules and Pragmata 🦋

bestie, get ready, this is the upgrade list and it's long but we're doing it, no skipping 😤 every single one:

• Archive::Tar — upgraded from version 2.04 to 2.04_01.
• bignum — upgraded from version 0.42 to 0.42_01.
• CPAN — upgraded from version 2.11 to 2.11_01.
• Digest — upgraded from version 1.17 to 1.17_01.
• Digest::SHA — upgraded from version 5.95 to 5.95_01.
• Encode — upgraded from version 2.80 to 2.80_01.
• ExtUtils::MakeMaker — upgraded from version 7.10_01 to 7.10_02.
• File::Fetch — upgraded from version 0.48 to 0.48_01.
• File::Spec — upgraded from version 3.63 to 3.63_01.
• HTTP::Tiny — upgraded from version 0.056 to 0.056_001.
• IO — upgraded from version 1.36 to 1.36_01.
• The IO-Compress modules — upgraded from version 2.069 to 2.069_001.
• IPC::Cmd — upgraded from version 0.92 to 0.92_01.
• JSON::PP — upgraded from version 2.27300 to 2.27300_01.
• Locale::Maketext — upgraded from version 1.26 to 1.26_01.
• Locale::Maketext::Simple — upgraded from version 0.21 to 0.21_01.
• Memoize — upgraded from version 1.03 to 1.03_01.
• Module::CoreList — upgraded from version 5.20160506 to 5.20170114_24.
• Net::Ping — upgraded from version 2.43 to 2.43_01.
• Parse::CPAN::Meta — upgraded from version 1.4417 to 1.4417_001.
• Pod::Html — upgraded from version 1.22 to 1.2201.
• Pod::Perldoc — upgraded from version 3.25_02 to 3.25_03.
• Storable — upgraded from version 2.56 to 2.56_01.
• Sys::Syslog — upgraded from version 0.33 to 0.33_01.
• Test — upgraded from version 1.28 to 1.28_01.
• Test::Harness — upgraded from version 3.36 to 3.36_01.
• XSLoader — upgraded from version 0.21 to 0.22, fixing a security hole in which binary files could be loaded from a path outside of @INC. [GH #15418] <https://github.com/Perl/perl5/issues/15418>

that last one is the main character of this list ngl, security hole patched, we love to see it 👑🔥

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📚 Documentation 📚

📝 Changes to Existing Documentation 📝

perlapio

• The documentation of PERLIO_DEBUG has been updated. ✨

perlrun

• The new -Di switch has been documented, and the documentation of PERLIO_DEBUG has been updated. ✨

docs getting the attention they deserve, as they should 💅

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🧪 Testing 🧪

• A new test script, t/run/switchDx.t, has been added to test that the new -Di switch is working correctly. 🎀

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🐛 Selected Bug Fixes 🐛

• The change to hashbang redirection introduced in Perl 5.24.0 — whereby perl would redirect to another interpreter (Perl 6) if it found a hashbang path which contains perl followed by 6 — has been reverted because it broke in cases such as #!/opt/perl64/bin/perl.

like, imagine being perl64 and getting redirected to Perl 6. the disrespect 😭 the change got undone and honestly? deserved.

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🫶 Acknowledgements 🫶

Perl 5.24.1 represents approximately 8 months of development since Perl 5.24.0 and contains approximately 8,100 lines of changes across 240 files from 18 authors. slay 💖

Excluding auto-generated files, documentation and release tools, there were approximately 2,200 lines of changes to 170 .pm, .t, .c and .h files.

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.24.1:

Aaron Crane, Alex Vandiver, Aristotle Pagaltzis, Chad Granum, Chris 'BinGOs' Williams, Craig A. Berry, Father Chrysostomos, James E Keenan, Jarkko Hietaniemi, Karen Etheridge, Leon Timmermans, Matthew Horsfall, Ricardo Signes, Sawyer X, Sébastien Aperghis-Tramoni, Stevan Little, Steve Hay, Tony Cook.

round of applause for the whole squad 👏👏👏 genuinely iconic.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker. y'all are seen and loved 🫶

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish. CPAN besties, this one's for you 🌸

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

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🐞 Reporting Bugs 🐞

If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the Perl bug database at <https://rt.perl.org/> . There may also be information at <http://www.perl.org/> , the Perl Home Page. 🔍

If you believe you have an unreported bug, please run the perlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case — we're not reading a whole novel, bestie, give us the mini version 📝✨ Your bug report, along with the output of perl -V, will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

If the bug you are reporting has security implications which make it inappropriate to send to a publicly archived mailing list, then see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue. 🤫🔐

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👀 SEE ALSO 👀

• The Changes file for an explanation of how to view exhaustive details on what changed.
• The INSTALL file for how to build Perl.
• The README file for general stuff.
• The Artistic and Copying files for copyright information.

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and that's the whole page, bestie 💖 this was perl v5.42.3, dated 2026-08-03, and it's the PERL5241DELTA(1) manual page. go forth and upgrade responsibly, mwah 🎀🦋✨