CVE-2026-57077: YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via an unbounded newline scan in newline_len

Severity: high (CVSS 7.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-16 · updated 2026-10-24
Weakness: CWE-125

Description

YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via an unbounded newline scan in newline_len. In the bundled libsyck newline_len and is_newline dereference the scan pointer, and the following byte for a "\r\n" pair, with no NUL-terminator or bounds check. During block-scalar lexing at a document boundary the scan runs one byte past the heap lexer buffer. This is an incomplete fix of CVE-2025-11683, on a lexer path the earlier fix did not cover. Any caller that runs Load or LoadFile on an untrusted document with a block scalar at a document boundary reaches the over-read.

Affected products

TODDR YAML::Syck: before 1.47 — fixed in 1.47

How to fix

Upgrade to a fixed version: TODDR YAML::Syck 1.47. Check the vendor advisory for mitigations.

References

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