# CVE-2026-41136: free5GC AMF missing default case in Content-Type switch in HTTPUEContextTransfer

> Attackers can send requests with unsupported Content-Type headers to cause the AMF to process uninitialized objects, potentially leading to crashes or undefined behavior.

- **Severity:** Medium 5.5 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/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:** Yes
- **Published:** 21 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** GHSA-r99v-75p9-xqm5, GO-2026-5613

## What is CVE-2026-41136?

CVE-2026-41136 is a medium-severity vulnerability in Free5gc Free5gc, published on 21 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

free5GC AMF provides Access & Mobility Management Function (AMF) for free5GC, an an open-source project for 5th generation (5G) mobile core networks. Prior to version 1.4.3, the `HTTPUEContextTransfer` handler in `internal/sbi/api_communication.go` does not include a `default` case in the `Content-Type` switch statement. When a request arrives with an unsupported `Content-Type`, the deserialization step is silently skipped, `err` remains `nil`, and the processor is invoked with a completely uninitialized `UeContextTransferRequest` object. Version 1.4.3 contains a fix.

Weakness: CWE-440 (Expected Behavior Violation)

## Which versions are affected by CVE-2026-41136?

3 open source packages ship an affected version, including github.com/free5gc/amf. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/free5gc/amf` | Go | All versions | None |
| `github.com/free5gc/amf` | Go | All versions to 1.4.3 | None |
| `github.com/free5gc/amf` | Go | All versions to 1.4.3 | None |

Products: Free5gc Amf, Free5gc Free5gc.

## How do I fix CVE-2026-41136?

Upgrade to a fixed version.

## Is CVE-2026-41136 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41136 exists.

## Other vulnerabilities in Free5gc Free5gc

- [CVE-2025-69248](https://insights.sbomify.com/CVE-2025-69248/): free5GC has Array Index Out of Bounds in AMF Leading to Denial of Service (medium 6.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-41136 and fix it if it is affected.

What it is: CVE-2026-41136 is a medium-severity vulnerability in Free5gc Free5gc, published on 21 Apr 2026. 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-2026-41136 exists.

Affected packages and fixed versions:
- github.com/free5gc/amf (Go): affected all versions; no fix listed
- github.com/free5gc/amf (Go): affected all versions up to 1.4.3; no fix listed
- github.com/free5gc/amf (Go): affected all versions up to 1.4.3; no fix listed

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-2026-41136/ (Markdown: https://insights.sbomify.com/CVE-2026-41136/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-41136
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-41136
- OSV: https://osv.dev/vulnerability/CVE-2026-41136

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-41136/
Summaries are generated and may contain mistakes; the official description above is the record.