CVE-2026-57075
CriticalCVSS 9.1Exploitation Probability (EPSS)
Low risk8th percentile - higher than 8% of all known CVEs
Summary
In YAML::Syck for Perl before version 1.47, an out-of-bounds read vulnerability exists in the syck_base64dec function. It uses a signed char index to access the b64_xtable array, causing reads before the table when bytes >= 0x80 are encountered. The vulnerability is triggered by default Load or LoadFile calls on untrusted YAML documents containing a !!binary scalar with a high-bit byte.
Risk Assessment
An attacker can cause out-of-bounds memory reads, potentially leaking sensitive information or causing unexpected application behavior. The vulnerability is especially dangerous as it requires no special privileges and is triggered with default settings.
Recommendation
Immediately update YAML::Syck to version 1.47 or later. If an update is not possible, avoid processing untrusted YAML documents containing !!binary type.
Original NVD description (English source)
YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec. The base64 decoder in the bundled libsyck indexes the 256-entry static table b64_xtable with a signed char, so any !!binary byte >= 0x80 sign-extends to a negative index and reads before the table. The decoder receives the raw bytes of any !!binary node, a standard YAML type not gated by $LoadBlessed or $LoadCode, so it is reached on the default Load path. Any caller that runs Load or LoadFile on an untrusted document containing a !!binary scalar with a high-bit byte triggers the read, and the value read can surface in the decoded result.