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perl-5.42.2
⭐ Starred 2013 / PerlIO::encoding
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

PerlIO::encoding - encoding layer

SYNOPSIS

use PerlIO::encoding;

open($f, "<:encoding(foo)", "infoo");
open($f, ">:encoding(bar)", "outbar");

use Encode qw(:fallbacks);
$PerlIO::encoding::fallback = FB_PERLQQ;

DESCRIPTION

This PerlIO layer opens a filehandle with a transparent encoding filter.

On input, it converts the bytes expected to be in the specified character set and encoding to Perl string data (Unicode and Perl's internal Unicode encoding, UTF-8). On output, it converts Perl string data into the specified character set and encoding.

When the layer is pushed, the current value of $PerlIO::encoding::fallback is saved and used as the CHECK argument when calling the Encode methods encode() and decode().

SEE ALSO

open, Encode, "binmode" in perlfunc, perluniintro