What’s Vulnerable › Vulnerabilities

CVE-2026-114117: Vyper 0.3.8 through 0.5.0b1 Optimizer Miscompilation of msg.value | K in Ternary Branches

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-21 · updated 2026-10-22
• Weakness: CWE-682

Description

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.

Affected products

• vyperlang vyper: from 0.3.8 through 0.5.0b1

References

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

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