What’s Vulnerable › Vulnerabilities

CVE-2026-114114: Vyper through 0.5.0b1 Literal Value Substitution via Multi-byte Characters

• Severity: medium (CVSS 5.3 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: 2026-10-21 · updated 2026-10-28
• Weakness: CWE-176

Description

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.

Affected products

• vyperlang vyper: from 0.1.0b1 before 0.1.0b12 — fixed in 0.1.0b12

How to fix

Upgrade to a fixed version: vyperlang vyper 0.1.0b12. Check the vendor advisory for mitigations.

References

• https://github.com/vyperlang/vyper/security/advisories/GHSA-r3c7-7xwm-6vfw
• https://www.vulncheck.com/advisories/vyper-through-0.5-0b1-literal-value-substitution-via-multi-byte-characters
• https://github.com/vyperlang/vyper/security/advisories/GHSA-r3c7-7xwm-6vfw

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