Vulnerability in Antlr Antlr4
CVE-2026-13502
A flaw has been found in antlr ANTLR4 up to 4.13.2. This affects the function ObjectInputStream.readObject of the file antlr4-maven-plugin/src/main/java/org/antlr/mojo/antlr4/GrammarDependencies.java of the component Maven Plugin. This manipulation causes time-of-check time-of-use. The attack is restricted to local execution. A high degree of complexity is needed for the attack. It is indicated that the exploitability is difficult. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
Vulnerability class: Race Condition
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.5 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.001 (1.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 1st percentile — 1.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000
Affected products
- Antlr Antlr4 — versions 4.13.0, 4.13.1, 4.13.2
Weakness classification (CWE)
References
- github.com/wooyun123/wooyun/issues/7 (issue-tracking, exploit)
- vuldb.com/cve/CVE-2026-13502 (third-party-advisory)
- vuldb.com/submit/838685 (third-party-advisory)
- vuldb.com/vuln/374498 (technical-description, vdb-entry)
- vuldb.com/vuln/374498/cti (signature, permissions-required)
Frequently asked questions
- What is CVE-2026-13502?
- CVE-2026-13502 is a medium-severity vulnerability in Antlr Antlr4, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 4.5/10. Published 2026-06-28.
- How severe is CVE-2026-13502?
- Medium severity. CVSS v3 base score is 4.5 out of 10.