CVE-2026-13500Public exploitNetwork attack vector

Code injection through crafted grammar actions

Published Jun 28, 2026 · Updated Jun 28, 2026

Code injection in ANTLR 4 4.13.0 through 4.13.2 allows remote attackers to embed executable code in generated parsers via grammar actions. The public record identifies OutputFile.java and the grammar action block handler but does not disclose the responsible function or exact unsafe operation. Exploitation requires an attacker-controlled grammar to be processed by the ANTLR tool; the record does not establish a listening service or the context in which injected code executes.

CVSS severity7.3
High
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in ANTLR 4 4.13.0 through 4.13.2 allows remote attackers to embed executable code in generated parsers via grammar actions. The public record identifies OutputFile.java and the grammar action block handler but does not disclose the responsible function or exact unsafe operation. Exploitation requires an attacker-controlled grammar to be processed by the ANTLR tool; the record does not establish a listening service or the context in which injected code executes.

The record

CVE
CVE-2026-13500
Published
Jun 28, 2026
Updated
Jun 28, 2026
Vendor
ANTLR
Product
ANTLR 4
Classifications
CWE-94, CWE-74
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.13.0
  2. Affected versionversion=4.13.1
  3. Affected versionversion=4.13.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ANTLR · ANTLR 4version=4.13.0; version=4.13.1; version=4.13.2

Published CVSS scores

5.5VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
7.5VulDBAV:N/AC:L/Au:N/C:P/I:P/A:P
7.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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