How severe is GHSA-9p8r-4xp4-gw5w?

GHSA-9p8r-4xp4-gw5w has a CVSS score of 3.7/10, rated LOW. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-9p8r-4xp4-gw5w?

GHSA-9p8r-4xp4-gw5w affects the following packages: vyper (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-9p8r-4xp4-gw5w?

Update vyper to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9p8r-4xp4-gw5w is resolved across your whole dependency graph.

How do I detect GHSA-9p8r-4xp4-gw5w in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for vyper. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-9p8r-4xp4-gw5w if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-9p8r-4xp4-gw5w?

O3 pinpoints whether GHSA-9p8r-4xp4-gw5w is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-9p8r-4xp4-gw5w actively exploited in the wild?

Yes. There are 1 known exploit references for GHSA-9p8r-4xp4-gw5w, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for GHSA-9p8r-4xp4-gw5w?

GHSA-9p8r-4xp4-gw5w has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 41th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-9p8r-4xp4-gw5w?

GHSA-9p8r-4xp4-gw5w is classified as Buffer Overflow (CWE-119). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-9p8r-4xp4-gw5w published, and has it been updated?

GHSA-9p8r-4xp4-gw5w was published on February 26, 2024 and was last updated on June 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

GHSA-9p8r-4xp4-gw5w

LOW

Vyper's `_abi_decode` vulnerable to Memory Overflow

Also known asCVE-2024-26149PYSEC-2024-164

Published

Feb 26, 2024

Updated

Jun 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk41th percentile-0.05%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐍vyper

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Summary

If an excessively large value is specified as the starting index for an array in _abi_decode, it can cause the read position to overflow. This results in the decoding of values outside the intended array bounds, potentially leading to bugs in contracts that use arrays within _abi_decode. The advisory has been assigned low severity, because it is only observable if there is a memory write between two invocations of abi_decode on the same input.

Proof of Concept

event Pwn:
    pass

@external
def f(x: Bytes[32 * 3]):
    a: Bytes[32] = b"foo"
    y: Bytes[32 * 3] = x

    decoded_y1: Bytes[32] = _abi_decode(y, Bytes[32])
    a = b"bar"
    decoded_y2: Bytes[32] = _abi_decode(y, Bytes[32])

    if decoded_y1 != decoded_y2:
        log Pwn()

Sending the following calldata results in Pwn being emitted.

0xd45754f8
0000000000000000000000000000000000000000000000000000000000000020
0000000000000000000000000000000000000000000000000000000000000060
ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa0

Patches

Patched in https://github.com/vyperlang/vyper/pull/3925, https://github.com/vyperlang/vyper/pull/4091, https://github.com/vyperlang/vyper/pull/4144, https://github.com/vyperlang/vyper/pull/4060.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`vyper`	all versions	0.4.0

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Vyper is a pythonic Smart Contract Language for the ethereum virtual mac…

github.comNVDJan 2025

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for vyper. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update vyper to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9p8r-4xp4-gw5w is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-9p8r-4xp4-gw5w is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-9p8r-4xp4-gw5w. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary If an excessively large value is specified as the starting index for an array in `_abi_decode`, it can cause the read position to overflow. This results in the decoding of values outside the intended array bounds, potentially leading to bugs in contracts that use arrays within `_abi_decode`. The advisory has been assigned low severity, because it is only observable if there is a memory write between two invocations of `abi_decode` on the same input. ## Proof of Concept ```vyper event Pwn: pass @external def f(x: Bytes[32 * 3]): a: Bytes[32] = b"foo" y: Bytes[32 * 3]

O3 Security · Impact-Aware SCA

Is GHSA-9p8r-4xp4-gw5w in your dependencies?

O3 detects GHSA-9p8r-4xp4-gw5w across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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