# CVE-2026-40247: free5gc UDR improper path validation allows unauthenticated access to Traffic Influence Subscriptions

> Unauthenticated attackers can read sensitive 5G subscription data due to improper path validation in the free5GC UDR service.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Apr 2026
- **Updated:** 17 Apr 2026
- **Also known as:** GHSA-x5r2-r74c-3w28, GO-2026-5741

## What is CVE-2026-40247?

CVE-2026-40247 is a high-severity missing authorization vulnerability in Free5gc Free5gc, published on 16 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

free5GC is an open-source implementation of the 5G core network. In versions 4.2.1 and below of the UDR service, the handler for reading Traffic Influence Subscriptions checks whether the influenceId path segment equals subs-to-notify, but does not return after sending the HTTP 404 response when validation fails. Execution continues and the subscription data is returned alongside the 404 response. An unauthenticated attacker with access to the 5G Service Based Interface can read arbitrary Traffic Influence Subscriptions, including SUPIs/IMSIs, DNNs, S-NSSAIs, and callback URIs, by supplying any value for the influenceId path segment. A patched version was not available at the time of publication.

Weakness: CWE-636 (Not Failing Securely), CWE-285 (Improper Authorization)

## Which versions are affected by CVE-2026-40247?

3 open source packages ship an affected version, including github.com/free5gc/udr. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/free5gc/udr` | Go | All versions | None |
| `github.com/free5gc/udr` | Go | All versions to 1.4.2 | None |
| `github.com/free5gc/udr` | Go | All versions to 1.4.2 | None |

Products: Free5gc Free5gc.

## How do I fix CVE-2026-40247?

No fix published yet.

## Is CVE-2026-40247 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40247 exists.

## Other vulnerabilities in Free5gc Free5gc

- [CVE-2026-44327](https://insights.sbomify.com/CVE-2026-44327/): free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler (critical 10.0)
- [CVE-2026-44329](https://insights.sbomify.com/CVE-2026-44329/): free5GC's SMF UPI management interface lacks auth middleware; unauthenticated topology read/write requests reach handlers (critical 10.0)
- [CVE-2026-44330](https://insights.sbomify.com/CVE-2026-44330/): free5GC's NEF nnef-pfdmanagement API is unauthenticated; forged bearer tokens can read PFD data and create/delete PFD subscriptions (critical 10.0)
- [CVE-2025-63679](https://insights.sbomify.com/CVE-2025-63679/): Memory corruption in n/a (critical 9.8)
- [CVE-2026-44315](https://insights.sbomify.com/CVE-2026-44315/): free5GC's NEF 3gpp-pfd-management API is unauthenticated; forged bearer tokens can create, read, and delete PFD transactions (critical 9.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40247 and fix it if it is affected.

What it is: CVE-2026-40247 is a high-severity missing authorization vulnerability in Free5gc Free5gc, published on 16 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-2026-40247 exists.

Affected packages and fixed versions:
- github.com/free5gc/udr (Go): affected all versions; no fix listed
- github.com/free5gc/udr (Go): affected all versions up to 1.4.2; no fix listed
- github.com/free5gc/udr (Go): affected all versions up to 1.4.2; 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-2026-40247/ (Markdown: https://insights.sbomify.com/CVE-2026-40247/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40247
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40247
- OSV: https://osv.dev/vulnerability/CVE-2026-40247

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40247/
Summaries are generated and may contain mistakes; the official description above is the record.