Security Advisories (1)
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

NAME

locale - Perl pragma to use or avoid POSIX locales for built-in operations

SYNOPSIS

my @x1 = sort @y;      # Native-platform/Unicode code point sort order
{
    use locale;
    my @x2 = sort @y;  # Locale-defined sort order
}
my @x3 = sort @y;      # Native-platform/Unicode code point sort order
                       # again

# Parameters to the pragma are to work around deficiencies in locale
# handling that have since been fixed, and hence these are likely no
# longer useful
use locale qw(:ctype :collate);    # Only use the locale for character
                                   # classification (\w, \d, etc.), and
                                   # for string comparison operations
                                   # like '$a le $b' and sorting.
use locale ':not_characters';      # Use the locale for everything but
                                   # character classification and string
                                   # comparison operations

use locale ':!numeric';            # Use the locale for everything but
                                   # numeric-related operations
use locale ':not_numeric';         # Same

no locale;             # Turn off locale handling for the remainder of
                       # the scope.

DESCRIPTION

This pragma tells the compiler to enable (or disable) the use of POSIX locales for built-in operations (for example, LC_CTYPE for regular expressions, LC_COLLATE for string comparison, and LC_NUMERIC for number formatting). Each use locale or no locale affects statements to the end of the enclosing BLOCK.

The pragma is documented as part of perllocale.