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CVE-2026-57076 CPAN Security Group
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CVE ID: CVE-2026-57076
Distribution: YAML-Syck
Versions: before 1.47
MetaCPAN: https://metacpan.org/dist/YAML-Syck
VCS Repo: https://github.com/toddr/YAML-Syck
YAML::Syck versions before 1.47 for Perl allow a heap use-after-free
via an anchor name reused as an anchors-table key in
syck_hdlr_add_anchor
Description
-----------
YAML::Syck versions before 1.47 for Perl allow a heap use-after-free
via an anchor name reused as an anchors-table key in
syck_hdlr_add_anchor.
In the bundled libsyck an anchor name allocated by syck_strndup is
stored both as node->anchor, freed when the node is freed, and as the
key in the parser's anchors table. Freeing the node frees the shared
key, and a later anchor redefinition makes st_delete compare against
the freed key, so st_strcmp reads freed heap memory. Anchors are a
standard YAML feature and need no special flags, so this is reached on
the default Load path.
Any caller that runs Load or LoadFile on an untrusted document that
redefines an anchor reaches the read of freed memory.
Problem types
-------------
- CWE-416 Use After Free
Solutions
---------
Upgrade to YAML-Syck 1.47 or later.
References
----------
https://metacpan.org/release/TODDR/YAML-Syck-1.47/changes
https://github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d8b.patch
--
Paul Johnson - [email protected]
