What is 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.
The record classifies CVE-2026-13502 under weakness classes CWE-367, CWE-362. Its CVSS v3 base vector states that the flaw requires local access to the host, needs low-privilege credentials, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 99 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 4.5 — MEDIUM
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R - CVSS v4.0 base score
- 2
CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P - EPSS (FIRST)
- 0.0% probability of exploitation in the next 30 days, higher than 63.9% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 4.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-06-28, last modified 2026-06-29
Is CVE-2026-13502 being exploited?
It currently carries a trending score of 45 in the Threadlinqs vulnerability feed.
Affected products and versions
- antlr: ANTLR4
How to fix CVE-2026-13502
No vendor patch reference has been recorded for CVE-2026-13502 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-13502
No threat campaign in the Threadlinqs corpus currently references CVE-2026-13502, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.
Sources
Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on .