CVE-2026-79675: NLTK: JVM argument injection bypass via per-call options in the NLTK Stanford wrappers (incomplete fix of CVE-2026-12841)

An attacker who controls the java_options parameter to any NLTK Stanford wrapper class can inject arbitrary JVM flags, including:

• -agentpath:/path/to/malicious.so – loads a native agent, achieving arbitrary code execution
• -javaagent:/path/to/malicious.jar – loads a Java agent for bytecode manipulation
• -agentlib:jdwp=transport=dt_socket,server=y,address=*:5005 – enables remote debugging, allowing remote code execution
• @/path/to/argfile – expands an argument file, which can smuggle any of the above

This is exploitable in scenarios where NLTK is deployed as a service and java_options is derived from user input, configuration files, or environment variables. The PR #3647 commit message explicitly states the fix was intended to cover “StanfordSegmenter, and GenericStanfordParser” but the implementation only validates in config_java().