Bug 2558035 (CVE-2026-114114)

Summary: CVE-2026-114114 vyper: Vyper: Silent constant substitution in compiled code via multi-byte character parsing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Vyper. The compiler improperly calculates source code positions by mixing character-based offsets with byte offsets during parsing. An attacker contributing source code can exploit this flaw by introducing multi-byte characters or invisible markers to shift internal code references. This flaw allows an attacker to silently substitute critical constants, such as addresses and numeric values, in the compiled code, compromising application integrity.
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Bug Depends On: 2558193    
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Description OSIDB Bzimport 2026-10-21 01:02:38 UTC 
Vyper 0.1.0b1 before 0.1.0b12, 0.1.0b14, and 0.4.1 through 0.5.0b1 mix character-based line offsets with Python's UTF-8 byte col_offset values in vyper/ast/parse.py, so multi-byte characters shift the source slices used to reconstruct later numeric literals. An attacker contributing source with non-ASCII identifiers that NFKC-normalize to ASCII, or an invisible byte-order mark, can silently substitute addresses, integers or other constants in compiled code.