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perl-5.42.2
⭐ Starred 2013 / vars
Security Advisories (1)
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.

NAME

vars - Perl pragma to predeclare global variable names

SYNOPSIS

use vars qw($frob @mung %seen);

DESCRIPTION

NOTE: For use with variables in the current package for a single scope, the functionality provided by this pragma has been superseded by our declarations, available in Perl v5.6.0 or later, and use of this pragma is discouraged. See "our" in perlfunc.

This pragma will predeclare all the variables whose names are in the list, allowing you to use them under use strict, and disabling any typo warnings for them.

Unlike pragmas that affect the $^H hints variable, the use vars and use subs declarations are not lexically scoped to the block they appear in: they affect the entire package in which they appear. It is not possible to rescind these declarations with no vars or no subs.

Packages such as the AutoLoader and SelfLoader that delay loading of subroutines within packages can create problems with package lexicals defined using my(). While the vars pragma cannot duplicate the effect of package lexicals (total transparency outside of the package), it can act as an acceptable substitute by pre-declaring global symbols, ensuring their availability to the later-loaded routines.

See "Pragmatic Modules" in perlmodlib.