/ 
YAML-Syck-0.64
/ YAML::Syck
Security Advisories (2)
CVE-2025-11683 (2025-10-16)

YAML::Syck versions before 1.36 for Perl has missing null-terminators which causes out-of-bounds read and potential information disclosure Missing null terminators in token.c leads to but-of-bounds read which allows adjacent variable to be read The issue is seen with complex YAML files with a hash of all keys and empty values. There is no indication that the issue leads to accessing memory outside that allocated to the module.

CVE-2026-4177 (2026-03-16)

YAML::Syck versions through 1.36 for Perl has several potential security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter. The heap overflow occurs when class names exceed the initial 512-byte allocation. The base64 decoder could read past the buffer end on trailing newlines. strtok mutated n->type_id in place, corrupting shared node data. A memory leak occurred in syck_hdlr_add_anchor when a node already had an anchor. The incoming anchor string 'a' was leaked on early return.

NAME

YAML::Syck - Fast, lightweight YAML loader and dumper

VERSION

This document describes version 0.64 of YAML::Syck, released July 22, 2006.

SYNOPSIS

use YAML::Syck;

# Set this for interoperability with other YAML/Syck bindings:
# e.g. Load('Yes') becomes 1 and Load('No') becomes undef.
$YAML::Syck::ImplicitTyping = 1;

$data = Load($yaml);
$data = LoadFile($file);
$yaml = Dump($data);
DumpFile($file, $data);

DESCRIPTION

This module provides a Perl interface to the libsyck data serialization library. It exports the Dump and Load functions for converting Perl data structures to YAML strings, and the other way around.

NOTE: If you are working with other language's YAML/Syck bindings (such as Ruby), please set $YAML::Syck::ImplicitTyping to 1 before calling the Load/Dump functions. The default setting is for preserving backward-compatibility with YAML.pm.

FLAGS

$YAML::Syck::Headless

Defaults to false. Setting this to a true value will make Dump omit the leading ---\n marker.

$YAML::Syck::SortKeys

Defaults to false. Setting this to a true value will make Dump sort hash keys.

$YAML::Syck::ImplicitTyping

Defaults to false. Setting this to a true value will make Load recognize various implicit types in YAML, such as unquoted true, false, as well as integers and floating-point numbers. Otherwise, only ~ is recognized to be undef.

$YAML::Syck::ImplicitUnicode

Defaults to false. For Perl 5.8.0 or later, setting this to a true value will make Load set Unicode flag on for every string that contains valid UTF8 sequences, and make Dump return a unicode string.

Regardless of this flag, Unicode strings are dumped verbatim without escaping; byte strings with high-bit set will be dumped with backslash escaping.

However, because YAML does not distinguish between these two kinds of strings, so this flag will affect loading of both variants of strings.

$YAML::Syck::UseCode

$YAML::Syck::LoadCode

$YAML::Syck::DumpCode

These control whether or not to try and eval/deparse perl source code.

CAVEATS

The current implementation bundles libsyck source code; if your system has a side-wide shared libsyck, it will not be used.

Tag names such as !!perl/hash:Foo is blessed into the package Foo, but the !hs/foo and !!hs/Foo tags are blessed into hs::Foo. Note that this holds true even if the tag contains non-word characters; for example, !haskell.org/Foo is blessed into haskell.org::Foo. Please use Class::Rebless to cast it into other user-defined packages.

SEE ALSO

YAML, JSON::Syck

http://www.yaml.org/

AUTHORS

Audrey Tang <cpan@audreyt.org>

COPYRIGHT

Copyright 2005, 2006 by Audrey Tang <cpan@audreyt.org>.

The libsyck code bundled with this library by why the lucky stiff, under a BSD-style license. See the COPYING file for details.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See http://www.perl.com/perl/misc/Artistic.html