GHSA-cx2q-hfxr-rj97 CVE-2023-42460 PYSEC-2023-191
Vyper's `_abi_decode` input not validated in complex expressions
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.67%
- Chance of exploitation in the next 30 days. Higher than 52.04% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-682 Incorrect Calculation
- Fix
0.3.10- Upgrade vyper to this version or later
Description
Impact
_abi_decode() does not validate input when it is nested in an expression. the following example gets correctly validated (bounds checked):
x: int128 = _abi_decode(slice(msg.data, 4, 32), int128)
however, the following example is not bounds checked
@external
def abi_decode(x: uint256) -> uint256:
a: uint256 = convert(_abi_decode(slice(msg.data, 4, 32), (uint8)), uint256) + 1
return a # abi_decode(256) returns: 257
the issue can be triggered by constructing an example where the output of _abi_decode is not internally passed to make_setter (an internal codegen routine) or other input validating routine.
Patches
https://github.com/vyperlang/vyper/pull/3626
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
References
Are there any links users can visit to find out more?
Affected versions
PyPI
| Package | Vulnerable | Fixed in |
|---|---|---|
| vyper | >= 0.3.4, < 0.3.10 |
0.3.10 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
vyper PyPI → 0.3.10
- pip
pip install --upgrade "vyper>=0.3.10"- poetry
poetry add "vyper>=0.3.10"- uv
uv add "vyper>=0.3.10"
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- Present
- Privileges required
- Low
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
CVSS 3.1 5.3
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Weakness
CWE-682: Incorrect Calculation
The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.
How to prevent it
- Implementation: Understand your programming language's underlying representation and how it interacts with numeric calculation. Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how your language handles numbers that are too large or too small for its underlying representation.
- Implementation: Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
- Implementation: Use the appropriate type for the desired action. For example, in C/C++, only use unsigned types for values that could never be negative, such as height, width, or other numbers related to quantity.
- Architecture and Design: Use languages, libraries, or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
- Architecture and Design: Use languages, libraries, or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
- Implementation: Examine compiler warnings closely and eliminate problems with potential security implications, such as signed / unsigned mismatch in memory operations, or use of uninitialized variables. Even if the weakness is rarely exploitable, a single failure may lead to the compromise of the entire system.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-2r3x-4mrv-mcxf Vyper: Memory corruption using function calls within tuples / nested calls | Medium | Also affects vyper |
| GHSA-4v7v-gqf9-ww2g Vyper: Call stack corruption when passing complex type containing non-base type members as argument | Medium | Also affects vyper |
| GHSA-vg88-3v92-rjx2 Vyper: Return inside for loop more than 1 level deep | Low | Also affects vyper |
| GHSA-3vcg-j39x-cwfm Vyper's `slice()` may elide side-effects when output length is 0 | Low | Also affects vyper |
| GHSA-qhr6-mgqr-mchm Vyper's `concat()` builtin may elide side-effects for zero-length arguments | Low | Also affects vyper |
| GHSA-h33q-mhmp-8p67 Vyper has a double eval in For List Iter | High | Also affects vyper |
| GHSA-4w26-8p97-f4jp AugAssign evaluation order causing OOB write within the object in Vyper | Critical | Also affects vyper |
| GHSA-2p94-8669-xg86 Vyper's sqrt doesn't define rounding behavior | High | Also affects vyper |
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