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01 Record

CVE-2026-55559

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

CriticalPUBLISHEDCNA: GitHub_M
CNA base score9.8 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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02 Description

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

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.78% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 55.7% of scored records. A rank, not a probability.
NVD base score
9.8 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD analysis status
Awaiting Analysis. NVD last modified this record on 2026-09-08.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-08-28 17:22Z2 MO AGO
Last updated
2026-08-28 19:58Z2 MO AGO
Reserved
2026-06-16
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
Critical (CVSS 9.8)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses
  • CWE-94Improper Control of Generation of Code ('Code Injection')Base
  • CWE-470Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')Base
  • CWE-1336Improper Neutralization of Special Elements Used in a Template EngineBase
Data version
5.2
Document digest
0561e8ea513f1fff187c6a0ce1856e430fc7d05b5cc1775ef390609b54132f1d

05 Affected products

VendorProductVersionsPlatforms
yamcsyamcs< 5.12.8, >= 5.13.0, < 5.13.2—

06 References