Yamcs: Remote Code Execution via instance-template argument YAML injection (createInstance)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-55559
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 20:18:28 UTC
Updated2026-09-08 21:08:37 UTC
DescriptionYamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs inserts templateArgs from POST /api/instances and PATCH /api/instances/{instance} into YAML through VarStatement.append in yamcs-core/src/main/java/org/yamcs/templating/VarStatement.java without YAML-context escaping. The rendered configuration is parsed by YamcsServer.createInstance and loaded by YamcsServerInstance, allowing an attacker to inject a services entry for org.yamcs.ProcessRunner. Deployments without security.yaml expose the operation through the guest superuser, while secured deployments require SystemPrivilege.CreateInstances. Successful exploitation executes commands as the Yamcs service account. This issue is fixed in versions 5.12.8 and 5.13.2.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

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

EPSS: 0.005520000 probability, percentile 0.441800000 (date 2026-09-08)

Problem Types: CWE-94 | CWE-470 | CWE-1336 | CWE-94 CWE-94: Improper Control of Generation of Code ('Code Injection') | CWE-470 CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') | CWE-1336 CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Yamcs Yamcs affected < 5.12.8 Not specified
CNA Yamcs Yamcs affected >= 5.13.0, < 5.13.2 Not specified

References

ReferenceSourceLinkTags
github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2 [email protected] github.com
github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8 [email protected] github.com
github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/yamcs/yamcs/commit/549f295cf8c5496a5e799d6bec2432ef976c82aa [email protected] github.com
github.com/yamcs/yamcs/commit/7192da1c49bdf5ab1d72e579a47766a7c43e87c8 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report