CVE-2025-21607: Success of Certain Precompile Calls not Checked in Vyper
Description
Vyper is a Pythonic Smart Contract Language for the EVM. When the Vyper Compiler uses the precompiles EcRecover (0x1) and Identity (0x4), the success flag of the call is not checked. As a consequence an attacker can provide a specific amount of gas to make these calls fail but let the overall execution continue. Then the execution result can be incorrect. Based on EVM's rules, after the failed precompile the remaining code has only 1/64 of the pre-call-gas left (as 63/64 were forwarded and spent). Hence, only fairly simple executions can follow the failed precompile calls. Therefore, we found no significantly impacted real-world contracts. None the less an advisory has been made out of an abundance of caution. There are no actions for users to take.
Classification
CVE ID: CVE-2025-21607
CVSS Base Severity: LOW
CVSS Base Score: 2.3
Affected Products
Vendor: vyperlang
Product: vyper
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.04% (probability of being exploited)
EPSS Percentile: 11.48% (scored less or equal to compared to others)
EPSS Date: 2025-02-12 (when was this score calculated)