Description

Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine. The `concat` built-in can write over the bounds of the memory buffer that was allocated for it and thus overwrite existing valid data. The root cause is that the `build_IR` for `concat` doesn't properly adhere to the API of copy functions (for `>=0.3.2` the `copy_bytes` function). A contract search was performed and no vulnerable contracts were found in production. The buffer overflow can result in the change of semantics of the contract. The overflow is length-dependent and thus it might go unnoticed during contract testing. However, certainly not all usages of concat will result in overwritten valid data as we require it to be in an internal function and close to the return statement where other memory allocations don't occur. This issue has been addressed in 0.4.0.

Classification

CVE ID: CVE-2024-22419

CVSS Base Severity: HIGH

CVSS Base Score: 7.3

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

Affected Products

Vendor: vyperlang

Product: vyper

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.41% (probability of being exploited)

EPSS Percentile: 60.54% (scored less or equal to compared to others)

EPSS Date: 2025-06-25 (when was this score calculated)

Stakeholder-Specific Vulnerability Categorization (SSVC)

SSVC Exploitation: poc

SSVC Technical Impact: partial

SSVC Automatable: true

References

https://nvd.nist.gov/vuln/detail/CVE-2024-22419
https://github.com/vyperlang/vyper/security/advisories/GHSA-2q8v-3gqq-4f8p
https://github.com/vyperlang/vyper/issues/3737
https://github.com/vyperlang/vyper/commit/55e18f6d128b2da8986adbbcccf1cd59a4b9ad6f

Timeline