# CVE-2026-5536: FedML-AI FedML gRPC server grpc_server.py sendMessage deserialization

> Remote attackers can exploit unsafe deserialization in the FedML gRPC server's sendMessage function to potentially execute arbitrary code.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Apr 2026
- **Updated:** 6 Apr 2026
- **Also known as:** GHSA-2fpx-xrc2-7qf3

## What is CVE-2026-5536?

CVE-2026-5536 is a medium-severity unsafe deserialization vulnerability in FedML-AI FedML, published on 5 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A weakness has been identified in FedML-AI FedML up to 0.8.9. Affected is the function sendMessage of the file grpc_server.py of the component gRPC server. Executing a manipulation can lead to deserialization. The attack may be performed from remote. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-502 (Deserialization of Untrusted Data), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-5536?

It affects 1 product.


Products: Tensoropera Fedml.

## How do I fix CVE-2026-5536?

No fix has been published for CVE-2026-5536 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5536 being exploited?

There is no known exploitation of CVE-2026-5536 in the wild and no public exploit code.

## Other vulnerabilities in FedML-AI FedML

- [CVE-2026-5535](https://insights.sbomify.com/CVE-2026-5535/): FedML-AI FedML MQTT Message FileUtils.java path traversal (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5536 and fix it if it is affected.

What it is: CVE-2026-5536 is a medium-severity unsafe deserialization vulnerability in FedML-AI FedML, published on 5 Apr 2026. 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-2026-5536 in the wild and no public exploit code.

Affected product: FedML-AI FedML. 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-2026-5536/ (Markdown: https://insights.sbomify.com/CVE-2026-5536/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5536
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5536
- OSV: https://osv.dev/vulnerability/CVE-2026-5536

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5536/
Summaries are generated and may contain mistakes; the official description above is the record.