CVE-2025-21607 Success of Certain Precompile Calls not Checked in Vyper

What is CVE-2025-21607?

CVE-2025-21607 is a low-severity vulnerability in vyperlang vyper, published on 14 Jan 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official 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. This issue is fixed in 0.4.1.

Weakness: CWE-670

Which versions are affected by CVE-2025-21607?

3 open source packages ship an affected version, including vyper. It affects 1 product.

Products include Vyperlang Vyper.

How do I fix CVE-2025-21607?

Upgrade vyper to 0.4.1 or later.

Is CVE-2025-21607 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-21607 exists.

Other vulnerabilities in vyperlang vyper

• CVE-2024-24563 Vyper array negative index vulnerability Critical 9.8
• CVE-2024-24561 Vyper bounds check on built-in `slice()` function can be overflowed Critical 9.8
• CVE-2023-39363 Vyper incorrectly allocated named re-entrancy locks Critical 9.1
• CVE-2022-24845 Integer bounds error in Vyper High 8.8
• CVE-2022-29255 Multiple evaluation of contract address in call in vyper High 8.2

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-vgf2-gvx8-xwc3, PYSEC-2025-33.