man > perl5261delta(1)

PERL5261DELTA(1)                  Perl Programmers Reference Guide                  PERL5261DELTA(1)

NAME
       perl5261delta - what is new for perl v5.26.1

DESCRIPTION
       This document describes differences between the 5.26.0 release and the 5.26.1 release.

       If you are upgrading from an earlier release such as 5.24.0, first read perl5260delta, which
       describes differences between 5.24.0 and 5.26.0.

Security
   [CVE-2017-12837] Heap buffer overflow in regular expression compiler
       Compiling certain regular expression patterns with the case-insensitive modifier could cause
       a heap buffer overflow and crash perl.  This has now been fixed.  [GH #16021]
       <https://github.com/Perl/perl5/issues/16021>

   [CVE-2017-12883] Buffer over-read in regular expression parser
       For certain types of syntax error in a regular expression pattern, the error message could
       either contain the contents of a random, possibly large, chunk of memory, or could crash
       perl.  This has now been fixed.  [GH #16025] <https://github.com/Perl/perl5/issues/16025>

   [CVE-2017-12814] $ENV{$key} stack buffer overflow on Windows
       A possible stack buffer overflow in the %ENV code on Windows has been fixed by removing the
       buffer completely since it was superfluous anyway.  [GH #16051]
       <https://github.com/Perl/perl5/issues/16051>

Incompatible Changes
       There are no changes intentionally incompatible with 5.26.0.  If any exist, they are bugs,
       and we request that you submit a report.  See "Reporting Bugs" below.

Modules and Pragmata
   Updated Modules and Pragmata
       •   base has been upgraded from version 2.25 to 2.26.

           The  effects  of  dotless  @INC on this module have been limited by the introduction of a
           more refined and accurate solution for removing '.' from @INC while  reducing  the  false
           positives.

       •   charnames has been upgraded from version 1.44 to 1.45.

       •   Module::CoreList has been upgraded from version 5.20170530 to 5.20170922_26.

Platform Support
   Platform-Specific Notes
       FreeBSD
           •   Building    with    g++    on    FreeBSD-11.0    has   been   fixed.    [GH   #15984]
               <https://github.com/Perl/perl5/issues/15984>

       Windows
           •   Support for compiling perl on Windows using Microsoft Visual Studio 2017  (containing
               Visual C++ 14.1) has been added.

           •   Building  XS  modules  with  GCC  6 in a 64-bit build of Perl failed due to incorrect
               mapping of  "strtoll"  and  "strtoull".   This  has  now  been  fixed.   [GH  #16074]
               <https://github.com/Perl/perl5/issues/16074>              [cpan              #121683]
               <https://rt.cpan.org/Public/Bug/Display.html?id=121683>        [cpan         #122353]
               <https://rt.cpan.org/Public/Bug/Display.html?id=122353>

Selected Bug Fixes
       •   Several  built-in  functions  previously  had  bugs that could cause them to write to the
           internal stack without allocating room for the item being written.  In  rare  situations,
           this  could have led to a crash.  These bugs have now been fixed, and if any similar bugs
           are introduced in future, they will be detected automatically in debugging  builds.   [GH
           #16076] <https://github.com/Perl/perl5/issues/16076>

       •   Using  a  symbolic  ref with postderef syntax as the key in a hash lookup was yielding an
           assertion       failure       on       debugging       builds.         [GH        #16029]
           <https://github.com/Perl/perl5/issues/16029>

       •   List  assignment  ("aassign")  could  in  some rare cases allocate an entry on the mortal
           stack      and      leave      the      entry      uninitialized.       [GH       #16017]
           <https://github.com/Perl/perl5/issues/16017>

       •   Attempting  to  apply  an  attribute  to  an "our" variable where a function of that name
           already exists could result in a NULL pointer being supplied where an  SV  was  expected,
           crashing perl.  [perl #131597] <https://rt.perl.org/Public/Bug/Display.html?id=131597>

       •   The  code  that  vivifies  a  typeglob out of a code ref made some false assumptions that
           could lead to a crash in cases such as "$::{"A"} = sub {}; \&{"A"}".  This has  now  been
           fixed.  [GH #15937] <https://github.com/Perl/perl5/issues/15937>

       •   "my_atof2"  no  longer reads beyond the terminating NUL, which previously occurred if the
           decimal     point     is     immediately     before     the     NUL.      [GH     #16002]
           <https://github.com/Perl/perl5/issues/16002>

       •   Occasional  "Malformed UTF-8 character" crashes in "s//" on utf8 strings have been fixed.
           [GH #16019] <https://github.com/Perl/perl5/issues/16019>

       •   "perldoc       -f       s"       now       finds       "s///".         [GH        #15989]
           <https://github.com/Perl/perl5/issues/15989>

       •   Some   erroneous   warnings   after   utf8  conversion  have  been  fixed.   [GH  #15958]
           <https://github.com/Perl/perl5/issues/15958>

       •   The "jmpenv" frame to catch Perl exceptions is set up lazily, and this used to be  a  bit
           too  lazy.   The  catcher  is  now set up earlier, preventing some possible crashes.  [GH
           #11804] <https://github.com/Perl/perl5/issues/11804>

       •   Spurious  "Assuming  NOT  a  POSIX  class"  warnings  have  been  removed.   [GH  #16001]
           <https://github.com/Perl/perl5/issues/16001>

Acknowledgements
       Perl  5.26.1  represents approximately 4 months of development since Perl 5.26.0 and contains
       approximately 8,900 lines of changes across 85 files from 23 authors.

       Excluding auto-generated files, documentation and release tools, there were approximately 990
       lines of changes to 38 .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 5.26.1:

       Aaron Crane, Andy Dougherty, Aristotle Pagaltzis, Chris 'BinGOs' Williams,  Craig  A.  Berry,
       Dagfinn  Ilmari  Mannsåker,  David  Mitchell,  E.  Choroba, Eric Herman, Father Chrysostomos,
       Jacques Germishuys, James E Keenan, John SJ Anderson, Karl Williamson, Ken Brown, Lukas  Mai,
       Matthew Horsfall, Ricardo Signes, Sawyer X, Steve Hay, Tony Cook, Yves Orton, Zefram.

       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.

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 AT 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.

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.

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.

perl v5.38.2                                 2026-06-12                             PERL5261DELTA(1)