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perl-5.45.1
⭐ Starred 2013 / less
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

less - perl pragma to request less of something

SYNOPSIS

use less 'CPU';

DESCRIPTION

This is a user-pragma. If you're very lucky some code you're using will know that you asked for less CPU usage or ram or fat or... we just can't know. Consult your documentation on everything you're currently using.

For general suggestions, try requesting CPU or memory.

use less 'memory';
use less 'CPU';
use less 'fat';

If you ask for nothing in particular, you'll be asking for less 'please'.

use less 'please';

FOR MODULE AUTHORS

less has been in the core as a "joke" module for ages now and it hasn't had any real way to communicating any information to anything. Thanks to Nicholas Clark we have user pragmas (see perlpragma) and now less can do something.

You can probably expect your users to be able to guess that they can request less CPU or memory or just "less" overall.

If the user didn't specify anything, it's interpreted as having used the please tag. It's up to you to make this useful.

# equivalent
use less;
use less 'please';

BOOLEAN = less->of( FEATURE )

The class method less->of( NAME ) returns a boolean to tell you whether your user requested less of something.

if ( less->of( 'CPU' ) ) {
    ...
}
elsif ( less->of( 'memory' ) ) {

}

FEATURES = less->of()

If you don't ask for any feature, you get the list of features that the user requested you to be nice to. This has the nice side effect that if you don't respect anything in particular then you can just ask for it and use it like a boolean.

if ( less->of ) {
    ...
}
else {
    ...
}

CAVEATS

This probably does nothing.
This works only on 5.10+

At least it's backwards compatible in not doing much.