Yamcs's WebSocket subscription handlers omit the privilege checks their REST siblings enforce

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-55545: 0.45% estimated exploitation activity in the next 30 days; percentile 39.28 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Asset / scope: Yamcs 5.12.7 WebSocket topics (packets, algorithm-status, mdb-changes) Summary Several WebSocket subscription handlers do not perform the privilege check that their REST counterparts enforce, so a principal subscribing over WebSocket receives data the REST API would have scoped or denied. Root cause - packets (PacketsApi.subscribePackets) performs no ReadPacket check, while the REST siblings do (listPackets:128, streamPackets:256, subscribeContainers:538). A principal with a narrow ReadPacket scope receives the raw binary of all TM packets on the processor. - algorithm-status (ProcessingApi.subscribeAlgorithmStatus) performs no check, while REST getAlgorithmStatus enforces checkObjectPrivileges(ReadAlgorithm, ...) (:467). - mdb-changes (MdbOverrideApi.subscribeMdbChanges) performs no check, while base MDB reads require GetMissionDatabase. Remediation Bring each WebSocket subscription handler to parity with its REST sibling's privilege check (ReadPacket, ReadAlgorithm,…

Published by the source

28 Aug 2026, 17:10 UTC

Last modified by the source

28 Aug 2026, 17:25 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-fwww-cp23-7f5g

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-fwww-cp23-7f5g

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# Patch Next advisory brief: CVE-2026-55545

Advisory: Yamcs's WebSocket subscription handlers omit the privilege checks their REST siblings enforce
IDs: CVE-2026-55545, GHSA-fwww-cp23-7f5g
Record: https://patchnext.com/advisories/cve-2026-55545 (revision 2, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.yamcs:yamcs-core 5.13.2, 5.12.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.yamcs:yamcs-core: affected <= 5.12.7; >= 5.13.0, <= 5.13.1; fixed in 5.12.8, 5.13.2

## Suggested inspection (read-only)
- Maven org.yamcs:yamcs-core: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.yamcs:yamcs-core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-fwww-cp23-7f5g (OSV record GHSA-fwww-cp23-7f5g lists affected ranges: Maven org.yamcs:yamcs-core >=0 =5.13.0 <5.13.2 (fixed))
- Verified: https://github.com/advisories/GHSA-fwww-cp23-7f5g (GitHub-reviewed advisory GHSA-fwww-cp23-7f5g lists affected ranges: Maven org.yamcs:yamcs-core >=0 =5.13.0 <=5.13.1)

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