Vyper: Return inside for loop more than 1 level deep
VVE-2020-0002
Earlier today, we received a responsible disclosure of a potential issue from @michwill (developer of @curvefi) for Vyper users who use return statements inside for loops of nested internal calls. Returning inside a for loop causes an invalid jump dest, reverting the transaction unnecessarily.
MWE:
@internal
def _baz():
for i in range(1):
return # Stack underflow happens here
@internal
def _bar():
self._baz()
@external
def foo():
self._bar()Impact
Impact is minor, it is unlikely a user would encounter this problem unless they were working with nested calls, and return statements inside calls. Even in that scenario, you would encounter a revert which should be noticeable with adequate testing. In limited circumstances, this could cause a DoS attack for public contracts under certain conditions.
Patches
Fixed in https://github.com/vyperlang/vyper/pull/2110. Please upgrade to Vyper 0.2.3
Workarounds
Not returning inside a for loop nested 2+ internal calls deep works as is:
@internal
def _baz():
for i in range(1):
pass
return # This works fine
@internal
def _bar():
self._baz()
@external
def foo():
self._bar()For more information
If you have any questions or comments about this advisory:
- Chat with us in our gitter
- Open an issue in https://github.com/vyperlang/vyper
- Email us at security@vyperlang.org
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Python (PyPI) | vyper | >= 0.1.0b10, < 0.2.3 | 0.2.3 |
Referencias
- Vector CVSS
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N- Debilidad (CWE)
CWE-691- Plataforma
- Python (PyPI)
- Paquete
vyper- Publicada
- 06.10.2026
- Actualizado
- 11.10.2026 15:18
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-vg88-3v92-rjx2 - CC BY 4.0
Historial de vulnerabilidades: vyper
Todas las vulnerabilidades publicadas de este paquete (Python (PyPI)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 47
- Primera → última
- 03.2020 10.2026
- Sin corrección
- 5
- Explotada en ataques
- 0
Distribución por gravedad
- Crítica 3
- Alta 14
- Media 20
- Baja 10
Divulgaciones por año
- 2020: 1
- 2021: 5
- 2022: 4
- 2023: 14
- 2024: 14
- 2025: 6
- 2026: 3
-
Vyper: Return inside for loop more than 1 level deep esta entrada
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