CVE-2026-13503

A flaw was found in antlr ANTLR4. A remote attacker can exploit a path traversal vulnerability by manipulating the getImportedVocabFile function within the tokenVocab Grammar Option Handler component. This could allow unauthorized access to sensitive files and directories on the system.

Successful exploitation requires a specific scenario where an application using ANTLR4 is configured to accept and parse untrusted, attacker-supplied grammar files containing a manipulated tokenVocab option.

Impact Limitations: The vulnerability is strictly limited to information disclosure via path traversal. While a remote attacker can read sensitive files that the application has permissions to access, this flaw does not inherently allow for remote code execution (RCE), data corruption, or privilege escalation on the host system.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.