# CVE-2026-13503: antlr ANTLR4 tokenVocab Grammar Option TokenVocabParser.java getImportedVocabFile path traversal

> Remote attackers can exploit a path traversal flaw in ANTLR4's tokenVocab handler to read arbitrary files from the system.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jun 2026
- **Updated:** 29 Jun 2026
- **Also known as:** CLSA-2026-1791472866, CLSA-2026-1791480304, CLSA-2026-1793128354, CLSA-2026-1793128545, DEBIAN-CVE-2026-13503, GHSA-w346-wxvq-p3xr, MGASA-2026-0488, UBUNTU-CVE-2026-13503

## What is CVE-2026-13503?

CVE-2026-13503 is a medium-severity path traversal vulnerability in ANTLR4, published on 28 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability was detected in antlr ANTLR4 up to 4.13.2. Affected by this issue is the function getImportedVocabFile of the file tool/src/org/antlr/v4/parse/TokenVocabParser.java of the component tokenVocab Grammar Option Handler. The manipulation results in path traversal. The attack can be executed remotely. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-13503?


## How do I fix CVE-2026-13503?

No fix published yet.

## Is CVE-2026-13503 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-13503 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-13503 and fix it if it is affected.

What it is: CVE-2026-13503 is a medium-severity path traversal vulnerability in ANTLR4, published on 28 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-13503 exists.

Affected product: ANTLR4. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-13503/ (Markdown: https://insights.sbomify.com/CVE-2026-13503/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-13503
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-13503
- OSV: https://osv.dev/vulnerability/CVE-2026-13503

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-13503/
Summaries are generated and may contain mistakes; the official description above is the record.