CVE-2026-114114: Improper Handling of Unicode Encoding in vyperlang vyper
Description
Vyper versions 0.1.0b1 before 0.1.0b12, 0.1.0b14, and 0.4.1 through 0.5.0b1 have a vulnerability in the handling of Unicode encoding in the parsing of source code. The issue arises from mixing character-based line offsets with Python's UTF-8 byte column offsets, causing multi-byte characters to shift source slices used for reconstructing numeric literals. This allows an attacker to use non-ASCII identifiers that normalize to ASCII or invisible byte-order marks to silently substitute addresses, integers, or other constants in compiled code.
CVSS v4.0
Score 6.0medium
Affected software
vyperlang
vyper
vyperlang
vyper
vyperlang
vyper
pkg:pypi/vyperRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in vyperlang's vyper parser (in vyper/ast/parse.py) involves improper handling of Unicode encoding where character-based line offsets are mixed with UTF-8 byte column offsets. This causes multi-byte characters to shift the source slices used to reconstruct numeric literals, enabling an attacker to craft source code with non-ASCII identifiers or invisible byte-order marks that normalize to ASCII, resulting in silent substitution of critical constants such as addresses or integers in the compiled output.
Potential Impact
An attacker who can contribute source code with specially crafted non-ASCII identifiers or invisible byte-order marks can cause the compiler to silently substitute addresses, integers, or other constants in the compiled smart contract code. This can lead to unexpected behavior or security issues in the deployed contracts. The CVSS 4.0 score is 6.0 (medium severity), indicating a moderate risk with network attack vector, low attack complexity, and requiring user interaction and partial impact on integrity.
Mitigation Recommendations
No explicit patch or remediation information is provided in the input data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid compiling source code containing non-ASCII identifiers or invisible byte-order marks that could exploit this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-20T21:48:58.503Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ad80c0c2cdf04f6568caa66
Added to database: 10/21/2026, 00:49:16 UTC
Last enriched: 10/21/2026, 01:03:47 UTC
Last updated: 10/21/2026, 01:08:20 UTC
Views: 6
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