Threats Tagged 'cve-2026-57076'

This security update for perl-YAML-Syck addresses multiple memory-safety vulnerabilities in the libsyck library that are exploitable via the default YAML::Syck::Load() function when processing untrusted input. The fixed issues include out-of-bounds reads and use-after-free conditions that could lead to crashes or potentially other impacts. The update also hardens base64 decoding and enforces maximum depth limits to prevent stack exhaustion from deeply nested inputs.

YAML::Syck versions prior to 1.47 for Perl contain a use-after-free and double-free vulnerability triggered by redefinition or removal of anchor nodes during YAML parsing. This flaw causes the interpreter to crash, resulting in a denial of service when processing untrusted documents that redefine anchors mid-parse.

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.