Is CVE-2026-13500 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-13500 being exploited in the wild.

How severe is CVE-2026-13500?

High severity, with a CVSS score of 7.3, published 28 June 2026.

Is there a fix for CVE-2026-13500?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-13500 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-13500?

Check whether you run ANTLR4 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-13500: antlr ANTLR4 code injection in Grammar Action Block Handler

CVE-2026-13500 · Severity: high · CVSS 7.3 · Published 2026-06-28

ANTLR4 is a widely used tool for processing and translating structured text or code files. A security flaw in its grammar processing component allows for code injection, which could let an attacker run unauthorized commands on a system. This could lead to a full system compromise or unauthorized access to sensitive data if a developer processes a malicious grammar file.

Technologies: ANTLR4. Vendors: ANTLR.

Quick answers

Is CVE-2026-13500 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-13500 being exploited in the wild.
How severe is CVE-2026-13500?: High severity, with a CVSS score of 7.3, published 28 June 2026.
Which products and versions are affected?: ANTLR4 up to 4.13.2.
Is there a fix for CVE-2026-13500?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-13500 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-13500?: Check whether you run ANTLR4 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A code injection vulnerability exists in ANTLR4 versions up to 4.13.2 within the Grammar Action Block Handler component, specifically in the 'tool/src/org/antlr/v4/codegen/model/OutputFile.java' file. The flaw stems from improper neutralization of special elements (CWE-74) and improper control of code generation (CWE-94) when processing grammar actions. A remote attacker can exploit this by providing a specially crafted grammar file that, when processed by the ANTLR tool, executes arbitrary code. A public exploit has been disclosed, and as of the advisory date, the vendor has not provided a patch or official response.

Affected products

antlr ANTLR4 up to 4.13.2

Timeline

2026-06-28: disclosed: Public disclosure of the vulnerability and exploit.
2026-06-28: advisory: NVD/VulDB advisory published.

References

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