Bug 2501576 (CVE-2026-57077)

Summary: CVE-2026-57077 YAML::Syck: YAML::Syck: Information disclosure via out-of-bounds read
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in YAML::Syck. An out-of-bounds read vulnerability exists due to an unbounded newline scan during block-scalar lexing. A remote attacker could exploit this by providing a specially crafted YAML document, leading to potential information disclosure. This issue is an incomplete fix for a previously identified vulnerability.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2501652, 2501653    
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Description OSIDB Bzimport 2026-07-16 23:02:13 UTC 
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.