# CVE-2023-3040: Out of Bounds Access Leading to Undefined Behavior

> An out-of-bounds access in a debug function of lua-resty-json could cause denial of service if used on untrusted input, though it is not exploitable in normal environments.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Jun 2023
- **Updated:** 2 Jan 2025

## What is CVE-2023-3040?

CVE-2023-3040 is a low-severity denial of service vulnerability in Cloudflare lua-resty-json, published on 14 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A debug function in the lua-resty-json package, up to commit id 3ef9492bd3a44d9e51301d6adc3cd1789c8f534a (merged in PR #14) contained an out of bounds access bug that could have allowed an attacker to launch a DoS if the function was used to parse untrusted input data. It is important to note that because this debug function was only used in tests and demos, it was not exploitable in a normal environment.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2023-3040?

It affects 1 product.


Products: Cloudflare Lua-Resty-Json.

## How do I fix CVE-2023-3040?

No fix has been published for CVE-2023-3040 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-3040 being exploited?

There is no known exploitation of CVE-2023-3040 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-3040 and fix it if it is affected.

What it is: CVE-2023-3040 is a low-severity denial of service vulnerability in Cloudflare lua-resty-json, published on 14 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-3040 in the wild and no public exploit code.

Affected product: Cloudflare lua-resty-json. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-3040/ (Markdown: https://insights.sbomify.com/CVE-2023-3040/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-3040
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-3040
- OSV: https://osv.dev/vulnerability/CVE-2023-3040

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-3040/
Summaries are generated and may contain mistakes; the official description above is the record.