perl5263delta - what is new for perl v5.26.3


This document describes differences between the 5.26.2 release and the 5.26.3 release.

If you are upgrading from an earlier release such as 5.26.1, first read perl5262delta, which describes differences between 5.26.1 and 5.26.2.


[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.

[GH #16580] [cpan #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.

[GH #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.

[GH #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.

[GH #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.

[GH #16041]

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.

Modules and Pragmata

Updated Modules and Pragmata


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

Changes to Existing Diagnostics


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.

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.

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 . There may also be information at , 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 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:


This will send an email to the Perl 5 Porters list with your show of thanks.


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.