CVE-2026-66902: Google::Auth versions before 0.06 for Perl run a command named in an external_account credentials JSON via an ungated system call

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-04 · updated 2026-10-24
Weakness: CWE-78

Description

Google::Auth versions before 0.06 for Perl run a command named in an external_account credentials JSON via an ungated system call. The Pluggable subclass reads credential_source.executable.command from the credentials JSON and runs it as `system($command)`, a single argument call that passes the whole string to /bin/sh -c. The executable's environment_variables map from the same JSON is copied into %ENV first. No opt-in gate guards the call. make_creds selects the Pluggable subclass whenever credential_source.executable is present, so the path is reached from the standard Application Default Credentials flow, including a "type": "external_account" configuration read from the file named by GOOGLE_APPLICATION_CREDENTIALS. Configurations without credential_source.executable do not select this subclass and do not reach the call. Any caller that builds credentials from a configuration it does not fully control runs the embedded command with the privileges of the application process.

Affected products

CJCOLLIER Google::Auth: before 0.06 — fixed in 0.06

How to fix

Upgrade to a fixed version: CJCOLLIER Google::Auth 0.06. Check the vendor advisory for mitigations.

References

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