/ 
perl-5.42.1
⭐ Starred 2013 / Encode::TW
Security Advisories (4)
CVE-2026-13221 (2026-07-13)

Perl versions through 5.43.9 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk. When such branches are combined into a trie, the delta between the first branch and the shared tail is stored in a 16-bit field. A branch count above 65535 overflows the field, and the trie's match decision table is truncated with no warning or error. A pattern of this shape produces false positive matches (matching strings it should not) and false negative matches (failing to match strings it should). When such a pattern gates an access or filtering decision, the result is wrong.

CVE-2026-4176 (2026-03-29)

Perl versions from 5.9.4 before 5.40.4-RC1, from 5.41.0 before 5.42.2-RC1, from 5.43.0 before 5.43.9 contain a vulnerable version of Compress::Raw::Zlib. Compress::Raw::Zlib is included in the Perl package as a dual-life core module, and is vulnerable to CVE-2026-3381 due to a vendored version of zlib which has several vulnerabilities, including CVE-2026-27171. The bundled Compress::Raw::Zlib was updated to version 2.221 in Perl blead commit c75ae9cc164205e1b6d6dbd57bd2c65c8593fe94.

CVE-2026-57432 (2026-07-13)

Perl versions through 5.43.10 have an integer overflow in S_measure_struct leading to an out-of-bounds heap read in pack and unpack. S_measure_struct adds each item's size times its repeat count to a running total with no overflow check, so a large repeat count in a pack or unpack template wraps the signed SSize_t total negative. The @, X, and x position codes then guard their moves with a signed length comparison that passes when the length is negative, advancing the buffer pointer out of bounds. A template derived from untrusted input can read heap memory past the buffer and return it to the caller.

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

Encode::TW - Taiwan-based Chinese Encodings

SYNOPSIS

use Encode qw/encode decode/; 
$big5 = encode("big5", $utf8); # loads Encode::TW implicitly
$utf8 = decode("big5", $big5); # ditto

DESCRIPTION

This module implements tradition Chinese charset encodings as used in Taiwan and Hong Kong. Encodings supported are as follows.

Canonical   Alias		Description
--------------------------------------------------------------------
big5-eten   /\bbig-?5$/i	Big5 encoding (with ETen extensions)
        /\bbig5-?et(en)?$/i
        /\btca-?big5$/i
big5-hkscs  /\bbig5-?hk(scs)?$/i
            /\bhk(scs)?-?big5$/i
                              Big5 + Cantonese characters in Hong Kong
MacChineseTrad		Big5 + Apple Vendor Mappings
cp950		                Code Page 950 
                              = Big5 + Microsoft vendor mappings
--------------------------------------------------------------------

To find out how to use this module in detail, see Encode.

NOTES

Due to size concerns, EUC-TW (Extended Unix Character), CCCII (Chinese Character Code for Information Interchange), BIG5PLUS (CMEX's Big5+) and BIG5EXT (CMEX's Big5e) are distributed separately on CPAN, under the name Encode::HanExtra. That module also contains extra China-based encodings.

BUGS

Since the original big5 encoding (1984) is not supported anywhere (glibc and DOS-based systems uses big5 to mean big5-eten; Microsoft uses big5 to mean cp950), a conscious decision was made to alias big5 to big5-eten, which is the de facto superset of the original big5.

The CNS11643 encoding files are not complete. For common CNS11643 manipulation, please use EUC-TW in Encode::HanExtra, which contains planes 1-7.

The ASCII region (0x00-0x7f) is preserved for all encodings, even though this conflicts with mappings by the Unicode Consortium.

SEE ALSO

Encode