# CVE-2025-6566: oatpp Oat++ Deserializer.cpp deserializeArray stack-based overflow

> A stack-based buffer overflow in the oatpp library's JSON deserializer allows remote attackers to execute arbitrary code or cause denial of service.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Jun 2025
- **Updated:** 24 Jun 2025
- **Also known as:** GHSA-7c5x-vxj3-93v9

## What is CVE-2025-6566?

CVE-2025-6566 is a medium-severity memory corruption vulnerability in oatpp Oat++, published on 24 Jun 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability was found in oatpp Oat++ up to 1.3.1. It has been declared as critical. This vulnerability affects the function deserializeArray of the file src/oatpp/json/Deserializer.cpp. The manipulation leads to stack-based buffer overflow. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used.

Weakness: CWE-121 (Stack-based Buffer Overflow), CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2025-6566?

It affects 1 product.


Products: Oatpp Oat\+\+.

## How do I fix CVE-2025-6566?

No fix has been published for CVE-2025-6566 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-6566 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6566 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-6566 and fix it if it is affected.

What it is: CVE-2025-6566 is a medium-severity memory corruption vulnerability in oatpp Oat++, published on 24 Jun 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6566 exists.

Affected product: oatpp Oat++. 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-2025-6566/ (Markdown: https://insights.sbomify.com/CVE-2025-6566/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-6566
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-6566
- OSV: https://osv.dev/vulnerability/CVE-2025-6566

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-6566/
Summaries are generated and may contain mistakes; the official description above is the record.