Vyper Does Not Check the Success of Certain Precompile Calls

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.3 · CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2025-21607: 0.67% estimated exploitation activity in the next 30 days; percentile 52.11 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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. The fix is tracked in https://github.com/vyperlang/vyper/pull/4451.

Details

The relevant precompiles

EcRecover EcRecover is used in vyper's `ecrecover` built-in. As the precompile consumes 3000 gas, any execution after an out-of-gas EcRecover call has at most 47 gas left.

Identity - The Identity precompile is used in vyper to perform memory copy operations. As its cost is…

Published by the source

14 Jan 2025, 16:34 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

25 Oct 2026, 04:38 UTC

1. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-vgf2-gvx8-xwc3

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# Patch Next advisory brief: CVE-2025-21607

Advisory: Vyper Does Not Check the Success of Certain Precompile Calls
IDs: CVE-2025-21607, GHSA-vgf2-gvx8-xwc3
Record: https://patchnext.com/advisories/cve-2025-21607 (revision 2, source checked 25 Oct 2026, 04:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI vyper: affected every version

## Suggested inspection (read-only)
- `python -m pip show vyper`: prints the installed version. Run with the environment that serves production active.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on vyper.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-vgf2-gvx8-xwc3 (OSV record GHSA-vgf2-gvx8-xwc3 lists affected ranges: PyPI vyper >=0)

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