PERL5263DELTA(1)

💖 perl5263delta — what's new for perl v5.26.3 💖

okay so this whole page lives in the Perl Programmers Reference Guide, and it's the official tea on perl5263delta — everything that changed for perl v5.26.3. grab a snack, bestie, we're going through all of it 🍓

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🌸 DESCRIPTION 🌸

This doc spills the differences between the 5.26.2 release and the 5.26.3 release. periodt.

If you're upgrading from something even older, like 5.26.1, do yourself a favor and read perl5262delta first — that one covers the glow-up from 5.26.1 to 5.26.2. no skipping steps 💅

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🔒 Security 🔒

bestie this is the serious part. read it, fr fr.

🚨 [CVE-2018-12015] Directory traversal in module Archive::Tar 🚨

By default, Archive::Tar doesn't allow extracting files outside the current working directory. However, this secure extraction mode could be bypassed by putting a symlink and a regular file with the same name into the tar file. yes, that's as cursed as it sounds 😭

[GH #16580] <https://github.com/Perl/perl5/issues/16580> [cpan #125523] <https://rt.cpan.org/Ticket/Display.html?id=125523>

🚨 [CVE-2018-18311] Integer overflow leading to buffer overflow and segmentation fault 🚨

Integer arithmetic in Perl_my_setenv() could wrap when the combined length of the environment variable name and value exceeded around 0x7fffffff. This could lead to writing beyond the end of an allocated buffer with attacker supplied data. it's giving "oops, we wrote into the void" 💀

[GH #16560] <https://github.com/Perl/perl5/issues/16560>

🚨 [CVE-2018-18312] Heap-buffer-overflow write in S_regatom (regcomp.c) 🚨

A crafted regular expression could cause heap-buffer-overflow write during compilation, potentially allowing arbitrary code execution. a regex doing that. not okay. 🙈

[GH #16649] <https://github.com/Perl/perl5/issues/16649>

🚨 [CVE-2018-18313] Heap-buffer-overflow read in S_grok_bslash_N (regcomp.c) 🚨

A crafted regular expression could cause heap-buffer-overflow read during compilation, potentially leading to sensitive information being leaked. your secrets are NOT for the regex parser, bestie 😤

[GH #16554] <https://github.com/Perl/perl5/issues/16554>

🚨 [CVE-2018-18314] Heap-buffer-overflow write in S_regatom (regcomp.c) 🚨

A crafted regular expression could cause heap-buffer-overflow write during compilation, potentially allowing arbitrary code execution. yes, another one, same file, same vibe, equally not slay 🔥

[GH #16041] <https://github.com/Perl/perl5/issues/16041>

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🚫 Incompatible Changes 🚫

There are no changes intentionally incompatible with 5.26.2. If any exist, they are bugs, and we request that you submit a report. See "Reporting Bugs" below. so if something breaks, it's not a feature, it's a bug — go tell them, king 👑

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📦 Modules and Pragmata 📦

🎀 Updated Modules and Pragmata 🎀

• Archive::Tar has been upgraded from version 2.24 to 2.24_01.
• Module::CoreList has been upgraded from version 5.20180414_26 to 5.20181129_26.

look at them, thriving, evolving ✨

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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. (yes, the whole catalog lives over there 📚)

🆕 New Diagnostics 🆕

✨ New Errors ✨

• Unexpected ']' with no following ')' in (?[... in regex; marked by <-- HERE in m/%s/

(F) While parsing an extended character class a ']' character was encountered at a point in the definition where the only legal use of ']' is to close the character class definition as part of a '])', you may have forgotten the close paren, or otherwise confused the parser. relatable honestly, the parser got confused 🫠

• Expecting close paren for nested extended charclass in regex; marked by <-- HERE in m/%s/

(F) While parsing a nested extended character class like:

             (?[ ... (?flags:(?[ ... ])) ... ])
                                      ^

we expected to see a close paren ')' (marked by ^) but did not.

• Expecting close paren for wrapper for nested extended charclass in regex; marked by <-- HERE in m/%s/

(F) While parsing a nested extended character class like:

             (?[ ... (?flags:(?[ ... ])) ... ])
                                       ^

we expected to see a close paren ')' (marked by ^) but did not.

🔧 Changes to Existing Diagnostics 🔧

• Syntax error in (?[...]) in regex; marked by <-- HERE in m/%s/

This fatal error message has been slightly expanded (from "Syntax error in (?[...]) in regex m/%s/") for greater clarity. glow-up on the error message, honestly iconic 💅

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🫶 Acknowledgements 🫶

Perl 5.26.3 represents approximately 8 months of development since Perl 5.26.2 and contains approximately 4,500 lines of changes across 51 files from 15 authors. not them being busy 😭

Excluding auto-generated files, documentation and release tools, there were approximately 770 lines of changes to 10 .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 5.26.3:

Aaron Crane, Abigail, Chris 'BinGOs' Williams, Dagfinn Ilmari Mannsåker, David Mitchell, H.Merijn Brand, James E Keenan, John SJ Anderson, Karen Etheridge, Karl Williamson, Sawyer X, Steve Hay, Todd Rinaldo, Tony Cook, Yves Orton.

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. if you reported something: you ate, and you're in our hearts 💖

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://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. 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. tiny repro or it didn't happen, bestie 🎀

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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🌈 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 nice, it costs nothing and it's highkey appreciated 🫶

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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 — go forth, upgrade responsibly, and remember: read your delta docs, they're literally free lore ✨