CVE-2026-4177:
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.
1 issue postponed or untriaged:
CVE-2025-11683:
(postponed; to be fixed through a stable update)
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.
Among the 3 debian patches
available in version 1.36-2 of the package,
we noticed the following issues:
1 patch
where the metadata indicates that the patch has not yet been forwarded
upstream. You should either forward the patch upstream or update the
metadata to document its real status.
Standards version of the package is outdated.
wishlist
The package should be updated to follow the last version of Debian Policy
(Standards-Version 4.7.4 instead of
4.7.3).
![[bug history graph]](https://qa.debian.org/data/bts/graphs/liby/libyaml-syck-perl.png){kind=link}