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Fencer Intel
critical 9.1

CVE-2026-46621 json

Yamcs: Authenticated Remote Code Execution (RCE) via Jython Algorithm Code Injection

published 5mo ago modified 3mo ago also GHSA-2g95-6x5q-xjwj , EUVD-2026-44959

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 66%
public exploits
0
none known

Summary

Yamcs is a mission control framework. Prior to 5.12.7, the Yamcs script evaluation engine for Python algorithms dynamically compiled and evaluated user-controlled algorithm text using Jython through the JSR-223 ScriptEngine API without enforcing a secure sandbox, so an authenticated user with the ChangeMissionDatabase privilege could override an existing Python algorithm's logic through the mission database REST API and import and execute arbitrary Java classes such as java.lang.Runtime to achieve remote code execution on the underlying host operating system. This issue is fixed in versions 5.12.7 and 5.13.0, which disable algorithm editing by default.

Patch / fix

  • maven org.yamcs:yamcs-core 5.12.7
  • spaceapplications yamcs 5.12.7

Is CVE-2026-46621 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
3mo ago

Exploit prediction

1.12% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/yamcs/yamcs/security/advisories/GHSA-2g95-6x5q-xjwj referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
GitHub 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
maven org.yamcs:yamcs-core
<5.12.7
5.12.7

Affected products

  • yamcs yamcs

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.