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perl-5.45.1
⭐ Starred 2013 / Errno
Security Advisories (1)
CVE-2026-15534 (2026-08-09)

Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch. The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it. A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.

NAME

Errno - System errno constants

SYNOPSIS

use Errno qw(EINTR EIO :POSIX);

DESCRIPTION

Errno defines and conditionally exports all the error constants defined in your system errno.h include file. It has a single export tag, :POSIX, which will export all POSIX defined error numbers.

On Windows, Errno also defines and conditionally exports all the Winsock error constants defined in your system WinError.h include file. These are included in a second export tag, :WINSOCK.

Errno also makes %! magic such that each element of %! has a non-zero value only if $! is set to that value. For example:

my $fh;
unless (open($fh, "<", "/fangorn/spouse")) {
    if ($!{ENOENT}) {
        warn "Get a wife!\n";
    } else {
        warn "This path is barred: $!";
    } 
}

If a specified constant EFOO does not exist on the system, $!{EFOO} returns "". You may use exists $!{EFOO} to check whether the constant is available on the system.

Perl automatically loads Errno the first time you use %!, so you don't need an explicit use.

CAVEATS

Importing a particular constant may not be very portable, because the import will fail on platforms that do not have that constant. A more portable way to set $! to a valid value is to use:

if (exists &Errno::EFOO) {
    $! = &Errno::EFOO;
}

AUTHOR

Graham Barr <gbarr@pobox.com>

COPYRIGHT

Copyright (c) 1997-8 Graham Barr. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.