CVE intelligence and bounded remediation

CVE-2021-32647 — Emissary is a P2P based data-driven workflow engine

Critical CVSS 9.1

Emissary is a P2P based data-driven workflow engine. Affected versions of Emissary are vulnerable to post-authentication Remote Code Execution (RCE). The [`CreatePlace`](https://github.com/NationalSecurityAgency/emissary/blob/30c54ef16c6eb6ed09604a929939fb9f66868382/src/main/java/emissary/server/mvc/internal/CreatePlaceAction.java#L36) REST endpoint accepts an `sppClassName` parameter which is used to load an arbitrary class. This class is later instantiated using a constructor with the following signature: `<constructor>(String, String, String)`. An attacker may find a gadget (class) in the application classpath that could be used to achieve Remote Code Execution (RCE) or disrupt the application. Even though the chances to find a gadget (class) that allow arbitrary code execution are low, an attacker can still find gadgets that could potentially crash the application or leak sensitive data. As a work around disable network access to Emissary from untrusted sources.

Severity
Critical
CVSS
9.1 (3.1)
Published
2021-06-01
CISA KEV
Not currently listed
Ecosystem
java/maven
Weaknesses
CWE-74, CWE-470

Affected products

  • nsa / emissary / 6.4.0

Matched remediation archetype

Command, code, expression, and template injection

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Check exposure

  • Trace untrusted values to process execution, interpreters, evaluators, template engines, dynamic imports, and administrative scripting features.
  • Determine whether the affected path is reachable across each trust boundary and which service account or host privilege it inherits.
  • Review configuration for optional execution features, unsafe compatibility modes, and shell invocation.

Remediate safely

  • Replace string-built commands or evaluated code with fixed operations and structured argument APIs that do not invoke a shell.
  • Use strict allowlists for operation identifiers and reject unexpected input before it reaches any interpreter.
  • Update the affected component and add inert regression tests covering metacharacters, encoding variants, and alternate request paths.

Authoritative sources

Complete CVE record and remediation plan

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