# CVE-2025-15539: Open5GS sgwc s11-handler.c sgwc_s11_handle_downlink_data_notification_ack denial of service

> Remote attackers can cause a denial of service in Open5GS by exploiting a flaw in the SGWC S11 handler, requiring a patch for mitigation.

- **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:** 18 Jan 2026
- **Updated:** 23 Feb 2026
- **Also known as:** GHSA-9g9c-c6jm-98g4

## What is CVE-2025-15539?

CVE-2025-15539 is a medium-severity denial of service vulnerability in Open5gs Open5gs, published on 18 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability was determined in Open5GS up to 2.7.6. Impacted is the function sgwc_s11_handle_downlink_data_notification_ack of the file src/sgwc/s11-handler.c of the component sgwc. This manipulation causes denial of service. The attack can be initiated remotely. The exploit has been publicly disclosed and may be utilized. Patch name: b4707272c1caf6a7d4dca905694ea55557a0545f. To fix this issue, it is recommended to deploy a patch. The issue report is flagged as already-fixed.

Weakness: CWE-404 (Improper Resource Shutdown or Release)

## Which versions are affected by CVE-2025-15539?

It affects 1 product.


Products: Open5gs Open5gs.

## How do I fix CVE-2025-15539?

No fix has been published for CVE-2025-15539 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-15539 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-15539 exists.

## Other vulnerabilities in Open5gs Open5gs

- [CVE-2024-40130](https://insights.sbomify.com/CVE-2024-40130/): Memory corruption in n/a (critical 9.8)
- [CVE-2021-28122](https://insights.sbomify.com/CVE-2021-28122/): Missing authorization in n/a (critical 9.8)
- [CVE-2021-25863](https://insights.sbomify.com/CVE-2021-25863/): Hardcoded credentials in n/a (high 8.8)
- [CVE-2025-41067](https://insights.sbomify.com/CVE-2025-41067/): Reachable Assertion vulnerability in Open5GS (high 8.7)
- [CVE-2025-41068](https://insights.sbomify.com/CVE-2025-41068/): Reachable Assertion vulnerability in Open5GS (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-15539 and fix it if it is affected.

What it is: CVE-2025-15539 is a medium-severity denial of service vulnerability in Open5gs Open5gs, published on 18 Jan 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-2025-15539 exists.

Affected product: Open5gs Open5gs. 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-2025-15539/ (Markdown: https://insights.sbomify.com/CVE-2025-15539/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-15539
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-15539
- OSV: https://osv.dev/vulnerability/CVE-2025-15539

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-15539/
Summaries are generated and may contain mistakes; the official description above is the record.