Yamcs vulnerable to unauthorized user enumeration via IAM API endpoints

Exploitation

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

CVSS

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

EPSS

• CVE-2026-44595: 1.06% estimated exploitation activity in the next 30 days; percentile 64.50 (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.

Summary The IAM API endpoints (listUsers, getUser, listGroups, and getGroup) in yamcs-core do not enforce the required SystemPrivilege.ControlAccess check. As a result, any authenticated user (even those with low or no privileges) can enumerate all user accounts in the system, including their usernames, superuser status, and group memberships. This constitutes a broken access control vulnerability (CWE-862) that leaks sensitive user information. Root Cause File: yamcs-core/src/main/java/org/yamcs/http/api/IamApi.java:125,180,357,372 listUsers(), getUser(), listGroups(), and getGroup() do not require SystemPrivilege.ControlAccess. Any authenticated user — regardless of privileges — can enumerate all users, their superuser status, and group memberships: Compare with properly protected endpoints: Impact Any authenticated user can: 1. List all user accounts in the system 2. Identify which accounts have superuser privileges 3. Use this information to target privileged accounts Proof of…

Published by the source

27 May 2026, 00:03 UTC

Last modified by the source

27 May 2026, 00:03 UTC

Source last checked

26 Oct 2026, 16:45 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-p2rj-mrmc-9w29

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# Patch Next advisory brief: CVE-2026-44595

Advisory: Yamcs vulnerable to unauthorized user enumeration via IAM API endpoints
IDs: CVE-2026-44595, GHSA-p2rj-mrmc-9w29
Record: https://patchnext.com/advisories/cve-2026-44595 (revision 1, source checked 26 Oct 2026, 16:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
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 5.12.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.yamcs:yamcs-core: affected < 5.12.7; fixed in 5.12.7

## 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://github.com/advisories/GHSA-p2rj-mrmc-9w29 (GitHub-reviewed advisory GHSA-p2rj-mrmc-9w29 lists affected ranges: Maven org.yamcs:yamcs-core >=0 <5.12.7)

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