ELA-1679-1 libyaml-syck-perl security update

Package	libyaml-syck-perl
Version	1.31-1+deb10u1 (buster), 1.29-1+deb9u1 (stretch)
Related CVEs	CVE-2025-11683 CVE-2026-4177

• CVE-2025-11683

  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.

• CVE-2026-4177

  Several 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.

For Debian 10 buster, these problems have been fixed in version 1.31-1+deb10u1.

For Debian 9 stretch, these problems have been fixed in version 1.29-1+deb9u1.

We recommend that you upgrade your libyaml-syck-perl packages.

Further information about Extended LTS security advisories can be found in the dedicated section of our website.