# CVE-2026-55545: Yamcs: WebSocket subscription handlers omit the privilege checks their REST siblings enforce

> Low-privilege users can access restricted telemetry and database changes via WebSocket due to missing privilege checks.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** GHSA-fwww-cp23-7f5g

## What is CVE-2026-55545?

CVE-2026-55545 is a medium-severity missing authorization vulnerability in yamcs, published on 28 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs WebSocket subscription handlers fail to enforce the privileges required by equivalent REST endpoints. PacketsApi.subscribePackets exposes the packets WebSocket topic without ObjectPrivilegeType.ReadPacket, ProcessingApi.subscribeAlgorithmStatus exposes the algorithm-status WebSocket topic without ObjectPrivilegeType.ReadAlgorithm, and MdbOverrideApi.subscribeMdbChanges exposes the mdb-changes WebSocket topic without SystemPrivilege.GetMissionDatabase. A low-privilege authenticated user can receive telemetry packets, algorithm status, and mission database change information outside the assigned authorization scope. This issue is fixed in versions 5.12.8 and 5.13.2.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-55545?

4 open source packages ship an affected version, including org.yamcs:yamcs-core.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.yamcs:yamcs-core` | Maven | All versions | 5.12.8 |
| `org.yamcs:yamcs-core` | Maven | All versions | 5.12.8 |
| `org.yamcs:yamcs-core` | Maven | From 5.13.0 | 5.13.2 |
| `org.yamcs:yamcs-core` | Maven | From 5.13.0 | 5.13.2 |

## How do I fix CVE-2026-55545?

Upgrade org.yamcs:yamcs-core to a fixed version for your release line: 5.12.8 or 5.13.2.

## Is CVE-2026-55545 being exploited?

There is no known exploitation of CVE-2026-55545 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55545 and fix it if it is affected.

What it is: CVE-2026-55545 is a medium-severity missing authorization vulnerability in yamcs, published on 28 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-55545 in the wild and no public exploit code.

Affected packages and fixed versions:
- org.yamcs:yamcs-core (Maven): affected all versions; fixed in 5.12.8
- org.yamcs:yamcs-core (Maven): affected all versions; fixed in 5.12.8
- org.yamcs:yamcs-core (Maven): affected from 5.13.0; fixed in 5.13.2
- org.yamcs:yamcs-core (Maven): affected from 5.13.0; fixed in 5.13.2

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-2026-55545/ (Markdown: https://insights.sbomify.com/CVE-2026-55545/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55545
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55545
- OSV: https://osv.dev/vulnerability/CVE-2026-55545

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55545/
Summaries are generated and may contain mistakes; the official description above is the record.