PERL5423DELTA(1)

💖 PERL5423DELTA 💖

okay bestie, welcome to the perldelta page for perl v5.42.3 — this is the Perl Programmers Reference Guide's lil' gossip drop about what's new, and I'm gonna walk you through every single crumb. no skimming, no skipping, we're doing the whole thing 💅

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✨ NAME ✨

perldelta — the tea on what's new for perl v5.42.3 🫖

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🌸 DESCRIPTION 🌸

So this doc spills the differences between the 5.42.2 release and the 5.42.3 release. that's it, that's the assignment 💖

If you're upgrading from something earlier, like 5.42.1, you gotta read perl5422delta first — that one covers the glow-up from 5.42.1 to 5.42.2. don't skip steps, bestie, it's giving prerequisite energy 🎀

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🔒 Security 🔒

okay this is the serious part. three CVEs got fixed. read up, no cap. 😤

CVE-2026-8376 — Buffer overflow in Perl_study_chunk

So Perl_study_chunk in regcomp_study.c was checking the size of the joined substring buffer in characters instead of bytes. 😭 On 32-bit builds, that can lead to an integer overflow of the size of the buffer, which leads to out-of-bounds writes. not the vibe. at all.

CVE-2026-57432 — Buffer overflow in S_measure_struct

If you call "pack" or "unpack" on a structure whose computed size is too big to fit in memory, an integer overflow could happen that would result in a buffer overflow. 💀 This usually happens because you embedded a large number as the repeat count for an item. so like... don't do that. or rather, it's fixed now, so you can, but historically: don't.

CVE-2026-13221 — Regex trie 16-bit field overflow

The trie optimization in the regex engine could overflow in an alternation with more than ~65k branches. This could cause both false positives and false negatives on such regular expressions. 🙈 imagine your regex lying to you. iconic behavior, terrible behavior, it's patched now bestie.

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🦋 Incompatible Changes 🦋

There are no changes intentionally incompatible with 5.42.2. 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 ✨

• Archive::Tar has been upgraded from version 3.04 to 3.12.
  • This fixes CVE-2026-9538, CVE-2026-42496, and CVE-2026-42497. slay 🔥
• Compress::Raw::Bzip2 has been upgraded from version 2.213 to 2.218.
• HTTP::Tiny has been upgraded from version 0.090 to 0.096.
  • This fixes CVE-2026-7010 and CVE-2026-7017.
• IO::Compress has been upgraded from version 2.213 to 2.223.
  • This fixes CVE-2025-15649, CVE-2026-48961, CVE-2026-48962, and CVE-2026-48959. that's four whole CVEs, we ate 🍓
• Module::CoreList has been upgraded from version 5.20260329_42 to 5.20260802_42.
• Socket has been upgraded from version 2.038 to 2.041.
  • This fixes CVE-2026-12087.
• Storable has been upgraded from version 3.37 to 3.37_01.
  • This fixes CVE-2026-57433.

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📚 Documentation 📚

💜 Changes to Existing Documentation 💜

We have attempted to update the documentation to reflect the changes listed in this document. If you find any we have missed, open an issue at <https://github.com/Perl/perl5/issues>. please do, we're literally asking 🙏

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🩺 Diagnostics 🩺

The following additions or changes have been made to diagnostic output, including warnings and fatal error messages. For the complete list of diagnostic messages, see perldiag.

⭐ New Diagnostics ⭐

💀 New Errors 💀

• Pack template structure size is too large

(F) You called "pack" or "unpack" to operate on a structure, whose computed size is too large to fit in memory. This usually happens as a result of embedding a large number as the repeat count for an item. yeah, it's that CVE-2026-57432 energy again, now with a friendly error message instead of a buffer overflow 🫶

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🧪 Testing 🧪

Tests were added and changed to reflect the other additions and changes in this release. the tests said "not on my watch" 💅

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👑 Acknowledgements 👑

Perl 5.42.3 represents approximately 4 months of development since Perl 5.42.2 and contains approximately 4,000 lines of changes across 120 files from 14 authors. the way that's a whole community effort 😭💖

Excluding auto-generated files, documentation and release tools, there were approximately 1,700 lines of changes to 59 .pm, .t, .c and .h files.

Perl continues to flourish into its fourth decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.42.3:

Aristotle Pagaltzis, Chris 'BinGOs' Williams, E. Choroba, Eric Herman, Karen Etheridge, Karl Williamson, Leon Timmermans, Paul Evans, Paul Marquess, Philippe Bruhat (BooK), Richard Leach, Steve Hay, Thibault Duponchelle, Tony Cook.

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. 🫶

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. 🌈

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 perl bug database at <https://github.com/Perl/perl5/issues>. There may also be information at <https://www.perl.org/>, the Perl Home Page. ✨

If you believe you have an unreported bug, please open an issue at <https://github.com/Perl/perl5/issues>. Be sure to trim your bug down to a tiny but sufficient test case. that's the move, bestie, minimal repro or it didn't happen 💅

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

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🙏 Give Thanks 🙏

If you wish to thank the Perl 5 Porters for the work we had done in Perl 5, you can do so by running the "perlthanks" program:

perlthanks

This will send an email to the Perl 5 Porters list with your show of thanks. go be sweet, it costs nothing 💖

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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 one's from perl v5.42.3, dated 2026-08-03, and you found it in the PERL5423DELTA(1) manual — mwah, go update your perl 💅✨🎀