CVE-2026-114117

MEDIUM 5.9

Vyper 0.3.8 through 0.5.0b1 Optimizer Miscompilation of msg.value | K in Ternary Branches

CVSS Score

5.9

EPSS Score

0.0%

EPSS Percentile

0th

Vyper 0.3.8 through 0.5.0b1 contains an optimizer miscompilation in which (msg.value | K) or (len(msg.data) | K), where K is any nonzero integer literal, is compiled to the constant 1 when used as a ternary expression branch under -O gas (the default) or -O codesize. Affected contracts use the wrong value in storage writes, arithmetic, indexes, return values, or events without warning or revert, which can record deposits incorrectly and lock funds.

CWE	CWE-682
Vendor	vyperlang
Product	vyper
Published	Oct 21, 2026

Stay Ahead of the Next One

Get instant alerts for vyperlang vyper

Be the first to know when new medium vulnerabilities affecting vyperlang vyper are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Affected Versions

vyperlang / vyper

0.3.8 ≤ 0.5.0b1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/vyperlang/vyper/security/advisories/GHSA-6j9c-gvcw-74fj vulncheck.com: https://www.vulncheck.com/advisories/vyper-0.3.8-through-0.5-0b1-optimizer-miscompilation-of-msg-value-k-in-ternary-branches

Credits

DELENE-TCHIO-ROMUALD