> CVE-2026-55559 [CRITICAL]

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PUBLISHED
2026-08-28 20:18
MODIFIED
2026-08-28 20:18
CVSS_SCORE V3
9.8
EPSS (Prob. Exploit)
0.78%
Top 44.4%
DATA SOURCES:
NVD đź”— 2026-08-28 CWE MITRE đź”— 2026-09-01 FIRST EPSS đź”— 2026-10-25 GITHUB đź”— 2026-10-29 OSV đź”— 2026-08-31

> DESCRIPTION

Yamcs 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.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EXPLOITABILITY
3.9
IMPACT
5.9

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
High (H)
Divulgation totale d'informations
I (Impact Intégrité)
Integrity Impact
High (H)
Modification totale des données possible
A (Impact Disponibilité)
Availability Impact
High (H)
Interruption totale du service possible

> RÉSUMÉ DES IMPACTS

Confidentialité
High
Divulgation totale d'informations
Intégrité
High
Modification totale des données possible
Disponibilité
High
Interruption totale du service possible

> WEAKNESSES

CWE-94 CWE-470 CWE-1336

> CWE DETAILED DESCRIPTIONS

CWE-94: Improper Control of Generation of Code ('Code Injection') - The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. | CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') - The product uses external input with reflection to select which classes or code to use, but it does not sufficiently prevent the input from selecting improper classes or code. | CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine - The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.

> GITHUB SECURITY ADVISORY

GHSA-73mf-m39p-wpm9 CRITICAL

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

AFFECTED PACKAGES:
MAVEN / org.yamcs:yamcs-core
<= 5.12.7
Fixed in: 5.12.8
MAVEN / org.yamcs:yamcs-core
>= 5.13.0, <= 5.13.1
Fixed in: 5.13.2

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

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

AFFECTED PACKAGES:
Unknown / Unknown
152 versions affected
ALIASES:
GHSA-73mf-m39p-wpm9

> HISTORIQUE DES MODIFICATIONS

Première apparition
28/08/2026 20:18
Source: NVD
📊 ENRICHISSEMENT 01/09/2026 06:02
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-94: Improper Control of Generation of Code ('Code Injection') - The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not n...
Total des modifications: 1 Dernière mise à jour: 1 month ago

> REFERENCES

https://github.com/yamcs/yamcs/commit/549f295cf8c5496a5e799d6bec2432ef976c82aa
https://github.com/yamcs/yamcs/commit/7192da1c49bdf5ab1d72e579a47766a7c43e87c8
https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8
https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2
https://github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9
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