Contract storage overwrite via floating-point slot rounding
Published Dec 13, 2023 · Updated Aug 2, 2024
Incorrect storage allocation in Vyper before 0.3.8 allows remote attackers to overwrite adjacent contract storage through large arrays. The storage allocator applies floating-point math.ceil to size_in_bytes divided by 32, allowing IEEE-754 rounding to undercount the required slots by one. Exploitation requires an affected compiler, an array near or above 2**64 elements, and a reachable contract operation that writes the colliding array index.
Summary
What happened
Incorrect storage allocation in Vyper before 0.3.8 allows remote attackers to overwrite adjacent contract storage through large arrays. The storage allocator applies floating-point math.ceil to size_in_bytes divided by 32, allowing IEEE-754 rounding to undercount the required slots by one. Exploitation requires an affected compiler, an array near or above 2**64 elements, and a reachable contract operation that writes the colliding array index.
The record
- CVE
- CVE-2023-46247
- Published
- Dec 13, 2023
- Updated
- Aug 2, 2024
- Vendor
- Vyper
- Product
- Vyper
- Classifications
- CWE-682, CWE-193, T1565.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 13, 2023CVE publishedPublication date reported by the CVE source.
- Aug 2, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.3.8
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Large-array contract storage overwrite examplesproof of concept · unverified
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Technologies
Your stack
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Your stack
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