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Medium

vyper's range(start, start + N) reverts for negative numbers

  • Disclosed: 25.04.2024
  • Updated: 11.10.2026 12:20

Summary

When looping over a range of the form range(start, start + N), if start is negative, the execution will always revert.

Details

This issue is caused by an incorrect assertion inserted by the code generation of the range (stmt.parse_For_range()):

https://github.com/vyperlang/vyper/blob/9136169468f317a53b4e7448389aa315f90b95ba/vyper/codegen/stmt.py#L286-L287

This assertion was introduced in https://github.com/vyperlang/vyper/commit/3de1415ee77a9244eb04bdb695e249d3ec9ed868 to fix https://github.com/advisories/GHSA-6r8q-pfpv-7cgj. The issue arises when start is signed, instead of using sle, le is used and start is interpreted as an unsigned integer for the comparison. If it is a negative number, its 255th bit is set to 1 and is hence interpreted as a very large unsigned integer making the assertion always fail.

PoC

vyper
@external
def foo():
    x:int256 = min_value(int256)
    # revert when it should not since we have the following assertion that fails:
    # [assert, [le, min_value(int256), max_value(int256) + 1 - 10]],
    for i in range(x, x + 10):
        pass

Patches

patched in v0.4.0, specifically, https://github.com/vyperlang/vyper/pull/3679 disallows this form of range().

Impact

Any contract having a range(start, start + N) where start is a signed integer with the possibility for start to be negative is affected. If a call goes through the loop while supplying a negative start the execution will revert.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Python (PyPI) vyper >= 0.3.8, < 0.4.0 0.4.0

References

CVSS score 5.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness (CWE)
CWE-681
Platform
Python (PyPI)
Package
vyper
Disclosed
25.04.2024
Updated
11.10.2026 12:20

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2024-246 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-ppx5-q359-pvwj - CC BY 4.0

Vulnerability history: vyper

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (47) in the archive
Total entries
47
First → latest
03.2020 10.2026
Without a fix
5
Exploited in attacks
0

Severity breakdown

  • Critical 3
  • High 14
  • Medium 20
  • Low 10

Disclosures per year

Severity:
  1. vyper's range(start, start + N) reverts for negative numbers this entry
    Medium · 5.3 CVE-2024-32481 >= 0.3.8, < 0.4.0 0.4.0
  2. Vyper negative array index bounds checks
    Critical · 9.8 CVE-2024-24563 < 0.4.0 0.4.0
  3. Vyper's bounds check on built-in `slice()` function can be overflowed
    Critical · 9.8 CVE-2024-24561 < 0.4.0 0.4.0
  4. concat built-in can corrupt memory in vyper
    High · 7.3 CVE-2024-22419 >= 0.3.0, < 0.4.0 0.4.0
  5. incorrect storage layout for contracts containing large arrays
    High · 7.5 CVE-2023-46247 < 0.3.8 0.3.8
  6. Vyper vulnerable to memory corruption in certain builtins utilizing `msize`
    High · 8.1 CVE-2023-42443 >= 0.3.4, < 0.3.10 0.3.10
  7. Vyper has incorrectly allocated named re-entrancy locks
    Critical · 8.7 CVE-2023-39363 >= 0.2.15, < 0.3.1 0.3.1
  8. Vyper vulnerable to incorrect ordering of arguments for kwargs passed to internal calls
    High · 7.5 CVE-2023-32059 < 0.3.8 0.3.8
  9. Vyper vulnerable to integer overflow in loop
    High · 7.5 CVE-2023-32058 < 0.3.8 0.3.8
  10. Vyper vulnerable to OOB DynArray access when array is on both LHS and RHS of an assignment
    High · 7.5 CVE-2023-31146 < 0.3.8 0.3.8
  11. vyper vulnerable to storage allocator overflow
    High · 7.5 CVE-2023-30837 < 0.3.8 0.3.8
  12. Incorrect success value returned in vyper
    High · 7.5 CVE-2023-30629 >= 0.3.1, < 0.3.8 0.3.8
  13. Multiple evaluation of contract address in call in vyper
    High · 7.5 CVE-2022-29255 < 0.3.4 0.3.4
  14. Vyper is a pythonic Smart Contract Language for the ethereum virtual machine. In affected versions, the return of `<iface>.returns_int128()` is not validated to fall within the bounds of `int128`. Thi
    High · 8.8 CVE-2022-24845 < 0.3.2 0.3.2
  15. Buffer Overflow in vyper
    High · 7.1 CVE-2022-24788 < 0.3.2 0.3.2
  16. Incorrect Comparison in Vyper
    High · 7.5 CVE-2022-24787 < 0.3.2 0.3.2
  17. Memory corruption when returning a literal struct with a private call inside of it
    High · 7.5 CVE-2021-41121 < 0.3.0 0.3.0
  18. Storage corruption due to variables overwritten by re-entrancy locks
    High ghsa-7f92-rr6w-cq64 >= 0.2.13, < 0.2.15 0.2.15

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