CVE-2026-46562: Yamcs Vulnerable to Remote Code Execution via Mission Database algorithm override

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 1.0%, percentile 62: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 62% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes org.yamcs:yamcs-core (Maven) < 5.12.7, fixed in 5.12.7. Check your lockfile, including transitive dependencies.

What it is

Yamcs is a mission control framework. Prior to 5.12.7, the Nashorn ScriptEngine used to evaluate user-supplied JavaScript algorithm text in yamcs-core/src/main/java/org/yamcs/algorithms/ScriptAlgorithmExecutorFactory.java was constructed without a ClassFilter, so a user with the ChangeMissionDatabase privilege could override an algorithm through the MdbOverrideApi.updateAlgorithm endpoint and supply JavaScript that reaches arbitrary Java classes (for example Java.type("java.lang.Runtime").getRuntime().exec(...)) to execute arbitrary OS commands as the Yamcs process; in the default configuration with no security.yaml the built-in guest user has superuser=true, making the issue reachable without authentication. This issue is fixed in versions 5.12.7 and 5.13.0, which disable algorithm editing by default.

From the GitHub advisory

Remote Code Execution via Mission Database algorithm override

Summary

The Nashorn ScriptEngine used to evaluate user-supplied algorithm text in MdbOverrideApi.updateAlgorithm is constructed without a ClassFilter, allowing a user with the ChangeMissionDatabase privilege to execute arbitrary Java code on the Yamcs server. In Yamcs's default configuration (no security.yaml), the built-in guest user has superuser=true, so the vulnerability is reachable without authentication.

Details

Vulnerable file: yamcs-core/src/main/java/org/yamcs/algorithms/ScriptAlgorithmExecutorFactory.java

Weakness type: CWE-94, CWE-95, CWE-470.

Product: org.yamcs:yamcs-core (Maven) · Assigned by: GitHub_M · Published: 2026-07-16

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.98% probability of exploitation activity in the next 30 days; percentile 62.

Timeline

• 2026-05-27 — GitHub-reviewed advisory GHSA-vmwp-vh32-rj75 published (critical)
• 2026-07-16 — CVE record last updated
• 2026-07-16 — CVE record published by GitHub_M

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-vmwp-vh32-rj75 github.com
2. CVE.org record CVE-2026-46562 cve.org
3. NVD entry CVE-2026-46562 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com

Critical Maven advisories · Today’s Security Digest