Is there a public PoC exploit available for CVE-2026-13501?

Yes, a public proof-of-concept exploit is available for CVE-2026-13501. Prioritise patching immediately. EPSS: 0.7%.

ANTLR4 CVE-2026-13501

Q: What is the CVSS score of CVE-2026-13501?

CVE-2026-13501 has a CVSS 4.0 base score of 1.9 (Low). CVSS vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.7%.

EUVD-2026-39999 LOW

Command Injection (CWE-77)

2026-06-28 VulDB

GHSA-q226-w36v-hhxv

Java Command Injection Antlr4 Antlr

1.9

CVSS 4.0 · Vendor: VulDB

Severity by source

Vendor (VulDB) PRIMARY

1.9 MEDIUM

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

5.3 MEDIUM

Local-only attack vector and low-privilege requirement strictly bound reach; limited C/I/A impact reflects constrained gofmt command injection scope with no scope change.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (VulDB).

CVSS VectorVendor: VulDB

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Analysis Generated

Jun 28, 2026 - 15:31 vuln.today

Severity Changed

Jun 28, 2026 - 15:22 NVD

MEDIUM LOW

CVSS changed

Jun 28, 2026 - 15:22 NVD

4.8 (MEDIUM) 1.9 (LOW)

DescriptionCVE.org

A security vulnerability has been detected in antlr ANTLR4 up to 4.13.2. Affected by this vulnerability is the function GoTarget of the file tool/src/org/antlr/v4/codegen/target/GoTarget.java of the component gofmt. The manipulation leads to command injection. The attack can only be performed from a local environment. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

AnalysisAI

Command injection in ANTLR4's Go code generation target (GoTarget.java) allows a local low-privilege attacker to execute arbitrary OS commands via unsanitized input passed to the gofmt invocation, affecting all versions up to 4.13.2. This vulnerability is scoped entirely to local environments such as developer workstations or CI/CD pipelines running ANTLR4 Go target code generation. A publicly available proof-of-concept exploit exists per the GitHub disclosure, but this is not confirmed as actively exploited (not in CISA KEV), and the CVSS 4.0 base score of 1.9 reflects its genuinely constrained real-world impact.

Technical ContextAI

ANTLR4 is a Java-based parser generator that supports multiple target programming languages. The affected component is the Go language target code generator, specifically the GoTarget function in tool/src/org/antlr/v4/codegen/target/GoTarget.java. This component invokes gofmt - Go's standard source formatter - as an external process during code generation. CWE-77 (Improper Neutralization of Special Elements used in a Command) identifies the root cause: user-controlled input (likely grammar file content or file path metadata) is passed unsanitized into the OS-level command construction that invokes gofmt, enabling shell metacharacter injection. The CPE string cpe:2.3:a:antlr:antlr4:*:*:*:*:*:*:*:* confirms all ANTLR4 releases through 4.13.2 carry this flaw in the Go target path.

RemediationAI

No vendor-released patch has been identified at time of analysis - the ANTLR4 maintainers did not respond to the coordinated disclosure. Monitor the official ANTLR4 GitHub repository and VulDB entry (https://vuldb.com/cve/CVE-2026-13501) for any upstream fix. As a primary compensating control, restrict the Go target code generation workflow to trusted, controlled grammar files only - do not process externally-supplied or user-controlled grammar files through ANTLR4's Go target until a patch is available, as this eliminates the attacker-controlled input path. In CI/CD environments, sandbox the ANTLR4 tool invocation using Docker containers with dropped capabilities (e.g., --cap-drop=ALL) or seccomp profiles to limit the blast radius of any injected commands - trade-off is added pipeline complexity. Restrict local system access to users who legitimately require ANTLR4 Go target code generation. If Go target generation is not required, avoid invoking the Go target entirely as a defensive measure.