CVE-2026-114114

MEDIUM 5.3

Vyper through 0.5.0b1 Literal Value Substitution via Multi-byte Characters

CVSS Score

5.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-176
Vendor	vyperlang
Product	vyper
Published	Oct 21, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Affected Versions

vyperlang / vyper

0.1.0b1 < 0.1.0b12

vyperlang / vyper

0.1.0b14 < 0.1.0b15

vyperlang / vyper

0.4.1 ≤ 0.5.0b1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

🔍 hyeon-Sec