/ 
perl-5.28.0-RC2
⭐ Starred 2013 / sort
Security Advisories (13)
CVE-2018-6798 (2018-04-17)

An issue was discovered in Perl 5.22 through 5.26. Matching a crafted locale dependent regular expression can cause a heap-based buffer over-read and potentially information disclosure.

CVE-2018-18312 (2018-12-05)

Perl before 5.26.3 and 5.28.0 before 5.28.1 has a buffer overflow via a crafted regular expression that triggers invalid write operations.

CVE-2026-8376 (2026-05-25)

Perl versions through 5.43.10 have a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds. Perl_study_chunk in regcomp_study.c checked the size of the joined substring buffer in characters rather than bytes. For a quantified fixed substring with a large minimum count, the byte length mincount * l could overflow SSize_t, producing an undersized SvGROW allocation; the subsequent copy writes past the end of the buffer. A caller that compiles an attacker-controlled regular expression on a 32-bit perl build triggers a heap buffer overflow at compile time.

CVE-2020-12723 (2020-06-05)

regcomp.c in Perl before 5.30.3 allows a buffer overflow via a crafted regular expression because of recursive S_study_chunk calls.

CVE-2020-10878 (2020-06-05)

Perl before 5.30.3 has an integer overflow related to mishandling of a "PL_regkind[OP(n)] == NOTHING" situation. A crafted regular expression could lead to malformed bytecode with a possibility of instruction injection.

CVE-2018-18311 (2018-12-07)

Perl before 5.26.3 and 5.28.x before 5.28.1 has a buffer overflow via a crafted regular expression that triggers invalid write operations.

CVE-2025-40909 (2025-05-30)

Perl threads have a working directory race condition where file operations may target unintended paths. If a directory handle is open at thread creation, the process-wide current working directory is temporarily changed in order to clone that handle for the new thread, which is visible from any third (or more) thread already running. This may lead to unintended operations such as loading code or accessing files from unexpected locations, which a local attacker may be able to exploit. The bug was introduced in commit 11a11ecf4bea72b17d250cfb43c897be1341861e and released in Perl version 5.13.6

CVE-2026-13221 (2026-07-13)

Perl versions through 5.43.9 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk. When such branches are combined into a trie, the delta between the first branch and the shared tail is stored in a 16-bit field. A branch count above 65535 overflows the field, and the trie's match decision table is truncated with no warning or error. A pattern of this shape produces false positive matches (matching strings it should not) and false negative matches (failing to match strings it should). When such a pattern gates an access or filtering decision, the result is wrong.

CVE-2026-4176 (2026-03-29)

Perl versions from 5.9.4 before 5.40.4-RC1, from 5.41.0 before 5.42.2-RC1, from 5.43.0 before 5.43.9 contain a vulnerable version of Compress::Raw::Zlib. Compress::Raw::Zlib is included in the Perl package as a dual-life core module, and is vulnerable to CVE-2026-3381 due to a vendored version of zlib which has several vulnerabilities, including CVE-2026-27171. The bundled Compress::Raw::Zlib was updated to version 2.221 in Perl blead commit c75ae9cc164205e1b6d6dbd57bd2c65c8593fe94.

CVE-2026-57432 (2026-07-13)

Perl versions through 5.43.10 have an integer overflow in S_measure_struct leading to an out-of-bounds heap read in pack and unpack. S_measure_struct adds each item's size times its repeat count to a running total with no overflow check, so a large repeat count in a pack or unpack template wraps the signed SSize_t total negative. The @, X, and x position codes then guard their moves with a signed length comparison that passes when the length is negative, advancing the buffer pointer out of bounds. A template derived from untrusted input can read heap memory past the buffer and return it to the caller.

CVE-2020-10543 (2020-06-05)

Perl before 5.30.3 on 32-bit platforms allows a heap-based buffer overflow because nested regular expression quantifiers have an integer overflow.

CVE-2023-47039 (2023-10-30)

Perl for Windows relies on the system path environment variable to find the shell (cmd.exe). When running an executable which uses Windows Perl interpreter, Perl attempts to find and execute cmd.exe within the operating system. However, due to path search order issues, Perl initially looks for cmd.exe in the current working directory. An attacker with limited privileges can exploit this behavior by placing cmd.exe in locations with weak permissions, such as C:\ProgramData. By doing so, when an administrator attempts to use this executable from these compromised locations, arbitrary code can be executed.

CVE-2023-47100

In Perl before 5.38.2, S_parse_uniprop_string in regcomp.c can write to unallocated space because a property name associated with a \p{...} regular expression construct is mishandled. The earliest affected version is 5.30.0.

NAME

sort - perl pragma to control sort() behaviour

SYNOPSIS

    use sort 'stable';		# guarantee stability
    use sort 'defaults';	# revert to default behavior
    no  sort 'stable';		# stability not important

    my $current;
    BEGIN {
	$current = sort::current();	# identify prevailing pragmata
    }

DESCRIPTION

With the sort pragma you can control the behaviour of the builtin sort() function.

A stable sort means that for records that compare equal, the original input ordering is preserved. Stability will matter only if elements that compare equal can be distinguished in some other way. That means that simple numerical and lexical sorts do not profit from stability, since equal elements are indistinguishable. However, with a comparison such as

{ substr($a, 0, 3) cmp substr($b, 0, 3) }

stability might matter because elements that compare equal on the first 3 characters may be distinguished based on subsequent characters.

Whether sorting is stable by default is an accident of implementation that can change (and has changed) between Perl versions. If stability is important, be sure to say so with a

use sort 'stable';

The no sort pragma doesn't forbid what follows, it just leaves the choice open. Thus, after

no sort 'stable';

sorting may happen to be stable anyway.

CAVEATS

As of Perl 5.10, this pragma is lexically scoped and takes effect at compile time. In earlier versions its effect was global and took effect at run-time; the documentation suggested using eval() to change the behaviour:

{ eval 'no sort "stable"';      # stability not wanted
  print sort::current . "\n";
  @a = sort @b;
  eval 'use sort "defaults"';   # clean up, for others
}
{ eval 'use sort qw(defaults stable)';     # force stability
  print sort::current . "\n";
  @c = sort @d;
  eval 'use sort "defaults"';   # clean up, for others
}

Such code no longer has the desired effect, for two reasons. Firstly, the use of eval() means that the sorting algorithm is not changed until runtime, by which time it's too late to have any effect. Secondly, sort::current is also called at run-time, when in fact the compile-time value of sort::current is the one that matters.

So now this code would be written:

{ no sort "stable";      # stability not wanted
  my $current;
  BEGIN { $current = sort::current; }
  print "$current\n";
  @a = sort @b;
  # Pragmas go out of scope at the end of the block
}
{ use sort qw(defaults stable);     # force stability
  my $current;
  BEGIN { $current = sort::current; }
  print "$current\n";
  @c = sort @d;
}