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CVE-2026-13503 antlr CVE debrief

CVE-2026-13503 is a path traversal vulnerability detected in antlr ANTLR4 up to version 4.13.2. The issue affects the function getImportedVocabFile in the file tool/src/org/antlr/v4/parse/TokenVocabParser.java of the component tokenVocab Grammar Option Handler. This vulnerability allows for remote exploitation, and a public exploit is available. The vendor, antlr, was contacted but did not respond. The vulnerability has a CVSS score of 5.5 and a severity rating of MEDIUM.

Vendor
antlr
Product
ANTLR4
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-28
Original CVE updated
2026-06-28
Advisory published
2026-06-28
Advisory updated
2026-06-28

Who should care

Organizations using ANTLR4 up to version 4.13.2 should be aware of this vulnerability and take steps to mitigate it. This vulnerability can be exploited remotely, and a public exploit is available, making it a significant risk. Security teams and developers using ANTLR4 should prioritize patching or mitigating this vulnerability.

Technical summary

The vulnerability is caused by a path traversal issue in the getImportedVocabFile function of the TokenVocabParser.java file. This function is part of the tokenVocab Grammar Option Handler in ANTLR4. The vulnerability has a CVSS score of 5.5 and a severity rating of MEDIUM. The CVSS vector is 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/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. The weakness associated with this vulnerability is CWE-22.

Defensive priority

This vulnerability should be prioritized for remediation due to its MEDIUM severity rating and the availability of a public exploit. Organizations should patch or mitigate this vulnerability as soon as possible to prevent potential attacks.

Recommended defensive actions

  • Patch ANTLR4 to version 4.13.3 or later
  • Implement input validation and sanitization for the tokenVocab Grammar Option Handler
  • Monitor for suspicious activity related to ANTLR4
  • Consider using a Web Application Firewall (WAF) to detect and prevent attacks
  • Perform a thorough inventory of systems using ANTLR4 and prioritize patching

Evidence notes

The CVE record and NVD detail pages provide information on this vulnerability. The CVE record was published on June 28, 2026, and the NVD detail page was last modified on June 28, 2026. The vulnerability was detected in ANTLR4 up to version 4.13.2, and a public exploit is available.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-13503 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-13503

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-13503 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-13503

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.